When was the Naval Base Subic Bay built?

In 1542, Spanish conquistador Juan de Salcedo sailed into Subic Bay but no port developed there because the main Spanish naval base would be established in the nearby Manila Bay. When the British captured this base in 1762, the Spanish were forced to find an alternate location and Subic Bay was found to be a strategic and superb port location. In 1884, King Alfonso XII of Spain decreed that Subic was to become "a naval port and the property appertaining thereto set aside for naval purposes."
The Americans captured the Spanish base in 1899 during the Philippine–American War, and controlled the bay until 1991. During this period, the naval facilities were greatly built up and expanded, including a new naval air station that was built in the early 1950s by slicing the top half from a mountain and moving the soil to reclaim a part of Subic Bay. In 1979, the area under American control was reduced from to when the Philippines claimed sovereign rule over the base. The presence of the American forces precipitated the start of a red-light district.

Subic Bay

Subic Bay is a bay on the west coast of the island of Luzon in the Philippines, about northwest of Manila Bay. An extension of the South China Sea, its shores were formerly the site of a major United States Navy facility named U.S. Naval Base Subic Bay, which is now the location of an industrial and commercial area known as the Subic Bay Freeport Zone under the Subic Bay Metropolitan Authority.

Today, water as well as the towns and establishments surrounding the bay are collectively referred to as Subic Bay. This includes the former US naval base at SBMA, Hanjin shipyard, Olongapo city, the town of Barrio Baretto, the Municipality of Subic, and the erstwhile US defence housing areas of Binictican and Kalayan housing, up to Morong in Bataan Province.

The bay was long recognized for its deep and protected waters, but development was slow due to lack of level terrain around the bay.

Following the destruction of the 1991 Mount Pinatubo eruption, the Americans closed the base, and the area was transformed into the Subic Bay Freeport Zone.

In 2012, controversy arose when a contracted shipping firm was accused of dumping toxic waste into Subic Bay. MT "Glenn Guardian", one of the vessels owned by a Malaysian firm, had collected some of domestic waste and about of bilge water from, a US Navy ship. Since the Malaysian firm was contracted by the US Navy, albeit under Philippine approval, this incident ignited anti-American sentiments in the Philippines from a single militant group.

The Pamulaklakin Nature Park is a reserve area of Binictican. Part of the 11 thousand hectares of forest is found at Subic Bay. The park was created by the Subic Bay Metropolitan Authority to supplement the income of the indigenous people. The term Pamulaklakin was derived from the native Ambala language, which means a herbal vine.

The majority of the wrecks in Subic Bay are a result of either the Spanish–American War in 1898 or of World War II, where a number of Japanese vessels were sunk by American aircraft.

Subic Bay is surrounded by the town of Subic and Olongapo City, both in the province of Zambales, and Morong in the province of Bataan. Development of Olongapo City was largely tied to the presence of the United States Navy base, once the largest U.S. military naval base in Asia. An arsenal and ship-repair facility was established at Subic Bay in 1885 by the then colonial power, Spain. Following the Spanish–American War, Subic Bay became a U.S. Navy and Marine base, and grew to be a major facility. Until 1991, it was the base of the United States 7th Fleet.In early 1991, after the collapse of protracted negotiations, the Philippine Senate rejected terms for renewal of the lease of the base. The U.S. Navy was already in the process of downsizing its Subic operations in June 1991, when Mount Pinatubo erupted. One of the largest volcanic eruptions in the last 100 years, it covered the Navy Base in volcanic ash and collapsed a significant number of structures. The last ship, USS "Belleau Wood", left on November 24, 1992.

Subic Bay Freeport Zone

Subic Bay Freeport Zone (SBFZ), which is known simply as Subic Bay or Subic is a special economic zone covering portions of Olongapo City and the towns of Subic in Zambales and Morong and Hermosa in Bataan.It is the Philippines' first successful case of a military base converted through volunteerism into a tax and duty-free zone, operated and managed by the Subic Bay Metropolitan Authority or SBMA. It covers the fenced area of the former U.S. Naval Base Subic Bay located in the southwest of Luzon Island in the Philippines.The harbor faces the Zambales Mountain Range to the west and the Subic Bay opening to the South China Sea. It is northwest of the Bataan Peninsula and southeast of Zambales Province.

SBFZ is 110 kilometers west of Manila. Manila Bay and the Bataan Peninsula separate SBFZ from Manila. The mountain ranges around the Subic Bay area and the deep natural harbor provide excellent and protected anchorage. In addition, these features make SBFZ naturally sheltered from typhoons as well as from the effects of an eruption of nearby Mt. Pinatubo.

Subic Bay Freeport Zone is in Region III (or Central Luzon Region) of the Philippines. It is one of the points in the growth triangle (and an engine for economic development) in the region. SBFZ is a supplier of services and products for the Central Luzon Development Program, a regional growth area composed of the provinces of Bulacan, Nueva Ecija, Tarlac, Pampanga, Bataan, and Zambales.

Subic Bay was converted into a commercial zone largely through the efforts of some 8,000 residents of nearby Olongapo City, under the leadership of their mayor, Richard Gordon, who volunteered to protect and preserve 8 billion dollars worth of facilities and property from looting and destruction. Subic has since been transformed and became a model for bases conversion into commercial use after the Cold War with blue chip companies like Coastal Petroleum, and Fed Ex pumping in over $3 billion of investments creating 70,000 jobs in the free port's first four years. It was host to the 4th APEC Leaders' Summit on November 24, 1996 and FedEx's Asia-Pacific hub, Asia-One, was also located in Subic Bay for almost ten years.

In addition to commercial use, Subic Bay is also a popular destination for weekend visitors from Metro Manila. Attractions include several beaches, an underwater aquarium, jungle survival tours, and duty-free shopping centers.

Subic International Raceway (SIR), the Philippines' first purpose-built motorsports venue, was opened in 1994 and situated near Subic Bay International Airport. It was established by local racing champion, Pocholo Ramirez, and his family. SIR was host to international racing events, such as the Asian Festival of Speed, Asian Formula 2000 and the Asian Formula Three Championship. It also hosted local races, such as the Philippine Touring Car Championship, Run What You Brung (RWYB) and Circuit Showdown. The racetrack ceased operations in 2010 after the end of its lease.

In 2013 Defense Secretary Voltaire Gazmin said that the Philippines intended to move military forces to the base in response to the territorial disputes in the South China Sea. The United States Navy is also seeking access on a rotational basis for ships and Marines, and is already conducting maritime patrol aircraft patrols from bases in the Philippines.

Subic Bay, the Philippines' first free port ("see, Port of Subic"), continues to be one of the country's major economic engines with more than 700 investment projects, including the 4th largest shipbuilding facility in the world (Hanjin Heavy Industries and Construction). Currently upgrading its port facilities through the Subic Bay Port Development Project and forging ties with the Clark Special Economic Zone in Angeles City to form the Subic-Clark Corridor via the 45-kilometer Subic-Clark-Tarlac Expressway, this historical bastion of western military might is now being positioned to become the most competitive international service and logistics center in Southeast Asia.

As a destination, Subic Bay has maintained its allure that once charmed US servicemen and their families. Its community continues to preserve and protect the bay, its surrounding forests and its flora and fauna. Interesting sights to see are its resident eco-tourism theme parks, the Ocean Adventure, the country's only open-sea marine park, Zoobic Safari, and the Pamulaklakin Nature Park which is home to the indigenous Aetas who once trained the U.S. Navy in jungle survival tactics.

In September 1762, the British invaded the Philippines and took over the Spanish main naval base in Manila Bay. This prompted the Spanish military to scout for the next promising naval station. The expedition returned with the good news for the naval command - a natural bounty and deep waters at Subic Bay. King Alfonso XII issued a decree in 1884 that declared Subic as "a naval port and the property appertaining thereto set aside for naval purposes." Construction of an arsenal and ship repair yard ensued March 8 the following year, as ordered by the new settlers' Naval Commission. Subic Bay's potential as naval station was realized by the Americans. Commodore George Dewey and his men engaged in a battle that destroyed the Spanish Army in 1898, and the Americans took over Subic Bay on December 10, 1899.

Subic, Zambales

Subic, officially the, is a  in the province of,. According to the, it has a population of people.

It is located along the northern coast of Subic Bay. Like Iba, the provincial capital, and neighboring Olongapo City, Subic is a fast-growing municipality/town and is expected to become a component city in the future, as well as increase in income. It is a former home of one of the largest US military facilities outside of the US mainland, the Subic Bay Naval Base.

The native Zambales inhabitants called the area "Hubek", which means "head of a plough"; Spanish missionary priests mispronounced the name as "Subiq". By the time of the American Occupation, "Subiq" was mispronounced as "Subig". Eventually, the name reverted to "Subiq", but the letter 'q' was replaced with letter 'c'.

In 1572, Juan de Salcedo, the Mexico-born Spanish conquistador and grandson of Miguel Lopez de Legazpi, founded Zambales during his exploration of northern Luzon. Subic was founded in the late 1607 when Augustinian friars headed by Rev. Fr. Rodrigo de San Miguel, this e're started that the natives in Subic especially Negritos and Aetas was Christianized under the rule of Spain

In 1902, Rear Admiral Robley D. Evans, Commander of the Asiatic Stations, directed 200 Marines for an expeditionary force for the first U.S. fleet exercise in Asian waters. Guns were erected on Grande Island and Admiral Evans laid plans for emergency repairs of the station at Subic Bay but was denied assistance by the U.S. Five years later, the U.S. Congress finally appropriated funds for a full-scale Subic Bay Naval Reservation. Words from then President Theodore Roosevelt goes: "If we are to exert the slightest influence in Western Asia, it is of the highest importance that we have a naval station in boto
Bay." Subic Bay is now on the rise of being one of the best training areas in the Corps. But with the U.S. - Japan tension heating up, appropriations for operation and maintenance of the base fell short. Hawaii came in the scene; funding of the development of Pearl Harbor as US main station in the Pacific earned the thumbs up of the Congress. Subic took its ill fate - a promising harbor was left as a small repair station.

US was drawn into the war in Europe; Filipinos and Americans worked hand in hand to prepare the battleships for World War I. Workers at Subic Bay also overhauled 26 German ships, that had been used to transport thousands of American troops to Europe. Likewise, this period gave way for different developments: Olongapo had a taste of some of its best years; the base was lined with trees and plants, and several recreational facilities were constructed.

The Japanese claimed Subic and Olongapo on January 10, 1942, days after the Pearl Harbor attack, bringing with them the devastation of World War II. Many Filipinos and Americans were killed, several buildings were destroyed, seven seaplanes were sunk, and lines of telephones and telegraphs were sabotaged. The Marines were ordered to withdraw into Bataan then soon to Corregidor, burning all buildings left standing after the Japanese attack. Filipinos torched all the war's ruins in Olongapo. Filipinos have been subjected to the cruelty of the Japanese for three years, after which the American made a forceful rebound and reoccupied the base on January 29, 1945.

The Marine station underwent massive reconstruction and was again ready for naval endeavors on September 26, 1945. Shortly after the marines resumed their duties, the Tydings-McDuffie Law set provision for Philippine independence and was granted on July 4, 1946. Nonetheless, the US maintained that it would still retain the country's military bases. The Philippines, acknowledging its frailty in the Cold War, entered into the RP-US Military Bases Agreement on March 14, 1947. The US was granted the right to retain sixteen military bases and to administrate the town of Olongapo. Several significant urbanization projects were orchestrated, but the most challenging was as gigantic as displacing half the part of a 1,200-foot mountain, that needed around 20 million man-hours, and required five years of labor - the exceptional air station and pier construction of the Seabees was the highlight of 1956 in Subic Bay. Another accomplishment at the height of the cold war was ammunition bunkers and buildings that occupied over 12,400 acres of the Southwestern part of Subic Bay. Set in the tropical rainforest, ammunition and ordnance from these facilities played a big role in the Vietnam War and in the Gulf War of 1991.

The original 1947 military pact between the Philippines and the US has been amended. The year 1979 witnessed a turning point for both countries - Philippines claimed a sovereign rule over the base and the US area of responsibility was reduced from 24,000 hectares to 6,300 hectares. What followed was a series of events that would change the course of Subic Bay forever. On June 15, 1991, volcanic ashes and debris rained over the base, devastating Subic Bay and neighboring provinces. Mt. Pinatubo's fury has left the US Navy and Air Force no option but to evacuate all their dependents. When Pinatubo's rage came to a halt, and American and Filipino personnel restored the base, bringing it back to business in no time. Uncertainty continued hovering the Philippine Senate with regard to the termination of the 1947 treaty. Months-long discussions were held; parliamentary proceedings were organized; and a pro-bases rally was staged, but to no avail. September 16, 1991 surfaced a conclusion - The US had to withdraw its forces and equipment from Clark and Subic, having received the rejection of 12 senators on the earlier proposed new treaty. The lowering of the Stars and Stripes followed suit. The Navy bid farewell to America's nine decades of military presence on Philippine soil.

Surprisingly the departure of the Americans did not spell doom. Subic has since been transformed and became a model for bases conversion into commercial use after the Cold War with blue chip companies like Coastal Petroleum, Enron and FedEx pumping in over $3 billion of investments creating 70,000 jobs in the free port's first four years. It was host to the 4th APEC Leaders' Summit on November 24, 1996 and FedEx's Asia-Pacific hub, Asia-One, was also located in Subic Bay for almost ten years.

In addition to commercial use, Subic Bay is also a popular destination for weekend visitors from Metro Manila. Attractions include several beaches, an underwater aquarium, jungle survival tours, racing and duty-free shopping centers. Both Subic Bay Freeport and the municipality itself sustain major improvement and continuing its growth as of today.
Most of Private schools are operated by Catholic Institution except for colleges.

In the, the population of Subic was people, with a density of.

The nearest airport is the Subic Bay International Airport situated south of the town proper.

The Port of Subic is the nearest seaport in Subic. The Port is operated and managed by the Subic Bay Metropolitan Authority (SBMA). It covers the fenced area of the former U.S. Naval Base Subic Bay located in the south-west of Luzon Island in the Philippines. Local fish port is also present at the coastal waters and some are in beach side.

The primary road that connects Subic to the other parts of the town is the Olongapo-Bugallon Road. most of the names of those streets based on the surnames of prominent residents and based on plants name. Most of the roads in Subic are made of concrete and asphalt while others are still dirts.

Diversion Road like Govic Highway are also commonly used by motorist from Barangay Matain to Barangay Manggahan, the purpose of this road is to lessen the traffic at the town proper and used by trucks especially going north of Castillejos and vice versa.

Another main road is the Philseco Road that ends from Barangay Asinan Proper down to Keppel Subic Shipyard (formerly Philippine Shipyard and Engineering Corporations). and Govic Highway Extension that ends from Castillejos down to Hanjin Shipyard which they exclusively used.

Electricity services were provided by the cooperative-run Zambales II Electric Cooperative, Inc. (ZAMECO II) which covers its Franchise Areas from Subic all the way to Cabangan since 1972.

Water services are provided by Subic Water District (SWD)(Not to be confused with Subic Water and Sewerage Company (Subic Water), which is a different water distribution company serving the neighboring city of Olongapo.).

Subic is politically subdivided into 16 barangays.
This is the complete list of municipal leaders such as Mayor, and Presidente Municipal since it was become municipality since 1902.
for list of mayors in Olongapo. See Olongapo

On 8 March 1885, the Spanish Navy authorized construction of the "Arsenal de Olongapo" and by the following September, work started at Olongapo. Both the harbor and its inner basin were dredged and a drainage canal was built, as the Spanish military authorities were planning to make Olongapo and their navy yard an "island." This canal also served as a line of defense and over which the bridge at the base's Main Gate passes. When the Arsenal was finished, the gunboats "Caviteño", "Santa Ana", and "San Quintín" were assigned for its defense. To complement these gunboats, coastal artilleries were planned for the east and west ends of the station, as well as on Grande Island.

U.S. Naval Base Subic Bay

Naval Base Subic Bay was a major ship-repair, supply, and rest and recreation facility of the Spanish Navy and subsequently the United States Navy located in Zambales, Philippines. The base was 262 square miles, about the size of Singapore. The Navy Exchange had the largest volume of sales of any exchange in the world, and the Naval Supply Depot handled the largest volume of fuel oil of any navy facility in the world. The naval base was the largest overseas military installation of the United States Armed Forces after Clark Air Base in Angeles City was closed in 1991. Following its closure in 1992, it was transformed into the Subic Bay Freeport Zone by the Philippine government.

Subic Bay's famous strategic location, sheltered anchorages, and deep water had first been made known when the Spanish explorer Juan de Salcedo reported the bay's existence to the Spanish authorities upon his return to Manila after Salcedo arrived in Zambales to establish the Spanish crown. It would be a number of years before the Spanish would consider establishing a base there.

Cavite, which had been home to most of the Spanish fleet in the Philippines, suffered from unhealthy living conditions and was vulnerable in time of war and bad weather because of its shallow water and lack of shelter. Therefore, a military expedition was sent to Subic Bay in 1868 with orders to survey the bay to find out if it would be a suitable site for a naval yard. The Spanish explored the entire bay and concluded that it had much promise and thus reported their findings to Cavite. This report was not well received in Manila, as the Spanish command was reluctant to move to the provincial isolation of Subic. Finally, in 1884, a Royal Decree declared Subic Bay as a naval port.

Seawalls, causeways and a short railway were built across the swampy tidal flats. To finish these projects, thousands of tons of earth and rock from Kalalake in Olongapo had to be brought in as fill. The magnitude of this quarrying was so huge that a hill eventually disappeared and became a lagoon in the area now known as Bicentennial Park.

The main entrance to the Arsenal was the West Gate, which still stands. This gate was equipped with gunports and also served as a jail. This gate was connected to the South Gate, which was near the water front, by a high wall of locally quarried stone.

Inside the Arsenal, the Spanish constructed a foundry, as well as other shops, which were necessary for the construction and repair of ships. The buildings were laid out in two rows on Rivera Point, a sandy patch of land jutting into the bay, and named after the incumbent Captain-General of the Philippines, Fernando Primo de Rivera. The Arsenal's showpiece was the station commandant's headquarters, which was a one-storey building of molave and narra woods, and stood near today's Alava Pier and had colored glass windows.

The Spanish navy yard was constructed in the area that was last occupied by the U.S. Naval Ship Repair Facility.

On 25 April 1898, Commodore George Dewey, Commander of the United States Asiatic Fleet, received word that war with Spain had been declared and was ordered to leave Hong Kong and attack the Spanish fleet in Manila Bay.

In the Philippines, Rear Admiral Patricio Montojo, realizing that Subic Bay would provide a more defensible position than Cavite, ordered his smaller ships and the batteries in Manila Bay to resist Dewey's fleet and deny them the entrance to Manila Bay. His other units would then use Subic Bay as a sally port, with which he could attack the American fleet's rear and cut off its supplies. On 26 April, Montojo arrived at Subic Bay aboard with seven other ships.

On the morning of the 27 April, "Castilla" was towed northeast of Grande Island to help control the western entrance to Subic Bay. The eastern entrance, which was between Grande and Chiquita Islands, had been blocked by the scuttling of "San Quintín" and two other vessels. On Grande Island, the four Ordóñez guns that had been shipped from Sangley Point were not yet installed. Meanwhile, a cable-laying ship, which was commandeered to lay mines, ended up putting only four of the 15 available mines in place.

In Hong Kong, Dewey purposely delayed his sailing until he received news from the U.S. Consul at Manila, Oscar F. Williams, about information about the strength and positions of the Spanish fleet. Williams told Dewey that Montojo and his fleet had sailed to Subic Bay.

On 30 April, Dewey sighted the islands of Luzon and thus ordered and to sail at full speed to Subic Bay to hunt for enemy ships. After seeing no enemy vessels at Subic, "Boston" and "Concord" signaled of their findings and rejoined the squadron underway to Manila.

At dawn of 1 May 1898, the American fleet entered Manila Bay. Once the ships closed to within of the Spanish fleet, Dewey ordered the Captain, Charles Gridley, of "Olympia" "You may fire when you are ready, Gridley." Montojo's fleet was destroyed, losing 167 men killed and 214 wounded. The Americans only suffered a handful of wounded.

In June 1898, nearly a thousand Spanish nationals left Olongapo and took refuge at Grande Island. By July, Dewey ordered and "Concord" to sail for Subic Bay to demand the surrender of Grande Island. When the American ships arrived, they saw the German cruiser at the island, but as the Americans cleared for action and started to head for "Irene", she fled around the other end of Grande. The Spanish garrison on the island did not resist and immediately surrendered to Captain Joseph Coghlan of "Raleigh".

During the Philippine–American War, the Americans focused on using the Spanish naval station at Sangley Point, largely ignoring Subic Bay, and the arsenal was occupied by Filipino forces. The Filipinos constructed a gun battery on top of a ridge using one of the guns on Grande Island.

In the summer of 1899, gunboats started patrolling Subic Bay and after realizing that the patrols would not stop, the Filipinos started to prepare to confront the Americans. During a routine patrol, the supply ship entered Subic Bay and came under fire from the newly constructed battery. "Zafiro" withdrew to Cavite and reported the incident to headquarters. The cruiser was then sent to Subic to silence the battery, but as she was withdrawing, the battery gave out one last shot, provoking the Americans.

On 23 September 1899, "Charleston", "Concord",, and "Zafiro" sailed into Subic Bay to destroy the battery. Upon clearing Kalaklan Point, "Monterey", equipped with guns, opened fire. Under this barrage, the battery was only able to fire one shot.

"Charleston" then sent a signal for 180 sailors and 70 Marines to land on Subic. Meanwhile, the other ships continued firing. The Filipinos then deployed into the town of Olongapo, returning fire with small arms. When the entire landing force was ashore, the ships ceased firing and the landing party entered the battery. In all, three charges of guncotton were placed on the battery, completely destroying it. The party then went back to their ships and sailed for Manila. While the battery was destroyed, the Filipino forces still held the navy yard as well as Olongapo.

In December 1899, the U.S. Army launched an operation to clear the countryside of Filipinos who were resisting American rule; 90 soldiers from the 32d U.S. Volunteers set out to capture Olongapo. As the soldiers were entering Santa Rita, just outside Olongapo, they met a pocket of resistance, but after returning fire, the armed Filipinos quickly scattered. The soldiers then proceeded to capture the navy yard.

When Rear Admiral John C. Watson learned of this action against the navy yard, he set out for Subic aboard, accompanied by. When the ships arrived, Watson was surprised that the U.S. Army was in complete possession of the navy yard. Watson then ordered Marine Captain John Twiggs Myers ashore with 100 Marines to secure the navy yard.

When the Marines found the highest flagpole on the navy yard, which was in front of the hospital, they immediately raised the American flag on 10 December 1899, one year after the Treaty of Paris was signed. The Marines then took responsibility for the navy yard while the Army took over administrative and operational control of Olongapo.

Drinking water was not available on the navy yard and so water details had to be sent to the village of Binictican, near the mouth of the river of the same name. Early during the occupation of Olongapo, the town was offered as a place of refuge for Filipinos who were sympathetic to the Americans. After an ambush of seven Marines, the inhabitants of the villages of Binictican and Boton were ordered to move into Olongapo or be declared outlaws. Those people who owned property in the two villages were given houses in Olongapo. Six days after the villagers settled in Olongapo, shelled Binictican and Boton and later 100 Marines completed the destruction.

The Marines then exercised civil authority over Olongapo and ordered municipal elections, appointed local policemen, gave away food to supplement poor harvests, supplied medical care and supplies, and set up a school for the teaching of the English language.

In 1900, the General Board of the United States Navy made a thorough study of the naval base building program and decided that the American fleet in the Philippines could be easily bottled up in either the Manila or Subic bays. They instead recommended Guimaras Island, south of Manila, as the most suitable site for the main American naval base in the Philippines. Admiral of the Navy George Dewey and Admiral George C. Remey, Commander of the Asiatic Fleet, disagreed. They thought Subic Bay held the greatest potential.

The Navy then called for another study with Remey as the senior member. This board then decided that Subic Bay was the most suitable and practicable place to build a naval base. A board of officers under Rear Admiral Henry C. Taylor was then appointed to develop a plan for the naval station. Extensive plans for fortifications, dockyards, drydocks, workshops, a hospital, a railroad linking Olongapo with Manila and storage facilities for 20,000 tons (18,000 metric tons) of coal were drawn up and submitted to the Congress.

The board requested an appropriation of $1 million ($ in 2021 dollars) to begin building the naval station. President Theodore Roosevelt, a strong supporter of the establishment of a naval station at Subic Bay, issued an Executive Order establishing the Subic Bay Naval Reservation.

Because of the establishment of the Subic Bay Naval Reservation in November 1901 more troops were assigned to Subic. When the Samar force returned at the beginning of March 1902, its personnel were divided between Olongapo and Cavite. Cavite, however, still continued to have the largest number of Marines anywhere in the Philippines and continued to be the headquarters of the U.S. Navy because of its proximity to Manila.

In December 1902, Rear Admiral Robley D. Evans, Commander of the Asiatic Fleet, directed the first fleet exercise in Asian waters. An expeditionary force of 200 Marines occupied and erected guns on Grande Island. The channels on each side of the island were mined, while vessels of the fleet operated in the bay itself. The exercise was highly successful and confirmed the Admiral's opinion of the strategic advantage of Subic Bay.

The value of Subic Bay as a training area was recognized as the Marines practiced movements in wild and difficult environment. Their building of bridges and roads was also considered to be excellent training.

In June 1907, as tensions with Japan mounted, orders were secretly issued for Army and Navy forces in the Philippines to concentrate at Subic Bay. A large supply of coal and certain advanced base materials including coastal defense guns were to be moved from Cavite. This plan, however, would be opposed by other military leaders and by Governor-General Leonard Wood. An acrimonious debate would emerge and plans to build a major base in the Philippines would be discarded. Roosevelt would be disappointed by this, wrote that the aforementioned decision was a humiliating experience, and instead pushed for the development of Pearl Harbor in Hawaii.

In 1917, as the United States was drawn into World War I, all the Navy's shipyards including Subic Bay began working at a feverish pace to prepare ships for sea. American and Filipino workers would take pride in their workmanship such that destroyers that were overhauled in Subic Bay became the vanguard of Admiral William Sims's convoy.

The Washington Naval Treaty of 1922 called for the limitation of naval armaments and included provisions that facilities for the repair and maintenance of American naval forces in the Philippines would be reduced. Shops were dismantled at the navy yard at Subic Bay and Fort Wint was reduced to caretaker status and personnel levels were cut.

The Japanese government kept a close eye on activities in the Philippines for violations of the 1922 treaty. During the typhoon season of 1928, VT Squadron Five which operated Martin torpedo aircraft out of Manila, arrived in Subic Bay on a routine training flight. A typhoon suddenly veered toward Subic Bay and the plane crews had to lay down ramps to haul the seaplanes up on the beach. The pontoons were filled with water and the planes lashed down. When the typhoon had passed, the undamaged planes were refloated and returned to their tenders at Manila.

Within three weeks, the squadron commander was informed of a Japanese complaint that the Navy had violated the treaty by increasing the facilities for plane handling at Subic Bay. The squadron commander was to provide all facts concerning the incident to the Office of the Governor-General of the Philippines so that a response could be made to the Tokyo government.

Even though the facilities at Subic Bay were greatly reduced under the Coolidge administration, some ship repair capability remained, including the Dewey Drydock. The Great Kantō earthquake occurred on 30 August 1923, devastating the Yokohama, Japan region. The transport ship "Merritt" set sail from Subic Bay in 72 hours loaded with Red Cross relief supplies and 200 Filipino nurses.

In the 1930s a tree-planting program had begun, transforming the naval station into a virtual tropical garden, with streets lined with coconut palms, hibiscus, and gardenias. Outside activities and sports were also promoted, with a golf course being laid out where Lowry Hall last stood.

By mid-1930, the Nazis had taken power in Germany and Japan was beginning to flex its military muscle. The United States Congress therefore authorized the release of funds with which to update the Coast Defenses of Manila and Subic Bays. President Franklin D. Roosevelt would complement this by ordering the integration of Filipino military forces into the newly created U.S. Army Forces in the Far East. General Douglas MacArthur, who had been serving as a military advisor to the government of the Commonwealth of the Philippines and was also Field Marshal of the Philippines, was ordered back to active duty with the rank of Lieutenant General with the title of Commander of the United States Army Forces in the Far East.

To prepare for eventual war, Dewey Drydock, which had been at Subic Bay for 35 years was towed to Mariveles Harbor, on the tip of the Bataan Peninsula, and scuttled there on 8 April 1942 to prevent the Japanese from deriving benefit from it.

The 4th Marine Regiment, which had been withdrawn from Shanghai in China, was ordered to withdraw to the Philippines. The first members of the regiment disembarked from "President Madison" at Subic Bay early on the morning of 1 November 1941. The remainder arrived on 1 December. The Marines were housed in temporary wooden barracks and in tents at the naval station and the rifle range.

The freshly arrived Marines were assigned to provide land defense for Subic Bay. Seaward defenses included the batteries at Fort Wint on Grande Island and a minefield, which had been laid off the entrance to Subic Harbor. As the Marines built beach defenses, Consolidated PBY-4 Catalinas from VP101 and VP-102 of Patrol Wing 10, which was stationed at Subic Bay, were conducting daily patrols off Luzon as a response to rumors that the Japanese were approaching the Philippines. On 11 December, seven Catalinas had just returned from patrol when Japanese Zeroes appeared and strafed the aircraft. One ensign was killed and all Catalinas sank to the bottom of Subic Bay's inner basin.

As the Japanese continued their advance through Luzon, telephone and telegraph lines between Manila and Olongapo were sabotaged; as a result, all Japanese in Olongapo were rounded up and turned over to the Provost Marshal. A priest had also been questioning Marines and Filipinos about sensitive matters such as troop positions and strength and after the Marines became suspicious, a search of the priest's belongings was ordered and a shortwave radio was found. Right there and then, the battalion commander convened a hearing and after intense interrogation, the priest confessed to being a member of the German-American Bund and had been a spy for the Japanese. He was then taken behind the church and shot by a Marine firing squad.

By 24 December, the situation at Subic had become hopeless and an order to destroy the station and withdraw was given. All buildings on the station were torched while Filipinos burned the entire town of Olongapo. All that remained on Subic was the former, and she was towed into a deep part of the bay and scuttled. All Marines withdrew to Bataan and eventually to Corregidor where they made their last stand.

Fort Wint, under the command of Colonel Napoleon Boudreau of the U.S. Army, was evacuated on 25 December. All equipment and supplies were destroyed. On 10 January 1942, soldiers of the Japanese Imperial Army's 14th Infantry Division marched into Olongapo and on 12 January, the Japanese commandeered native fishing boats to seize Grande Island. Subic Bay Naval Station was established with four companies of soldiers and a company of Kempeitai.

Within one week of the Japanese's occupation of Subic Bay and Grande Island, American PT boats at Cavite were ordered to attack a Japanese ship, which was anchored at Subic Bay, that was shelling American positions. "PT-31" and "PT-34" entered the bay separately. "PT-31" suffered engine trouble and ran aground on a reef. She was abandoned and destroyed. "PT-34" entered undetected and sunk a transport that was off-loading supplies. She then came under heavy fire but managed to escape undamaged.

"PT-32" was then ordered into Subic Bay and attacked and hit a light cruiser on 1 February. On 17 February, "PT-34" made a final but unsuccessful attack at Subic Bay after which all PT boats were ordered to leave the Philippines.

To protect Subic Bay, the Japanese garrisoned Fort Wint with anti-aircraft artillery and automatic weapons but did not repair the American guns nor build permanent fortification.

The Japanese then started shipbuilding at Subic Bay and began constructing wooden auxiliary vessels. Several hundred workers from occupied-China and Formosa were brought in as laborers, in addition to 1,000 Filipinos. Nine ships were built and shipped to Cavite for engine installation, however, none of the ships would see active service as they were destroyed by U.S. Navy aircraft.

One of the few buildings that were left standing from the bombing and subsequent torching of the station was the Catholic Church. The Japanese removed all religious articles and converted it into a movie theater and was later used to imprison Americans and Filipinos that had been captured. Those who died were buried behind the church in a common cemetery. When all the prisoners were shipped to Manila, the Japanese used the church as a stable for horses.

On 20 October 1944, four U.S. Army divisions aboard 650 U.S. Navy vessels landed at Palo, Leyte, fulfilling MacArthur's promise to return to the Philippines. On 13 December, the Japanese began evacuating civilians and non-essentials from Manila aboard "Oryoku Maru" and four other merchant ships. As the ship was heading for Japan, fighter aircraft from the aircraft carrier attacked the ships and left hundred of Japanese dead or wounded. "Oryoku Maru", heavily damaged with destroyed steering gear, pulled into Subic Bay. Throughout the night, the Japanese disembarked while the American and Allied prisoners, that were carried below decks, were left aboard.

The next morning, Japanese guards ordered the prisoners to come up on deck. As Navy aircraft began to strafe the ships, the prisoners started frantically running about. As the pilots approached, they recognized the white shapes as Americans or Allies and sharply pulled up, rocking their wings in recognition. Afterwards, the 1,360 surviving Allied prisoners were forced to strip and swim ashore where they were crowded into a fenced tennis court near the Spanish Gate.

Early the succeeding morning, three fighters scored two direct hits on "Oryoku Maru" and she burst into flames. After burning for two hours, she settled into the water about off Alava Pier.

When the planes had left the Japanese served the prisoners their first meal since leaving Manila two days before: two teaspoons of dry, raw rice. There was only one faucet from which the water trickled out so slowly that a prisoner was lucky if he managed one drink every 18 hours. Roll call was taken each morning. Those that had died during the night were buried in an improvised cemetery next to the seawall. After four days at Subic, only 450 survived the makeshift prison; they were subsequently sent to the labor camps in Japan.

By January 1945, the Japanese had all but abandoned Subic Bay. The U.S. Fifth Air Force had dropped 175 tons of bombs on Grande Island evoking only light fire from the skeleton Japanese force manning the anti-aircraft guns. The commander of Japanese forces in the Philippines, General Tomoyuki Yamashita, had withdrawn his forces into defensive mountain positions and ordered Colonel Sanenbou Nagayoshi to block Highway 7 near Subic Bay.

On 29 January, 40,000 American troops of the 38th Division and 34th Regimental Combat Team came ashore without resistance at San Antonio, Zambales, by the site of what became known as the San Miguel Naval Communications Station. The column advanced toward Subic Bay, meeting their first resistance at the bridge spanning the Kalaklan River near the Olongapo Cemetery. The Japanese, knowing that they would imminently lose the town, decided to destroy Olongapo. Eventually, the Japanese evacuated the town and the 34th Regiment took over.

The following day, Grande Island was taken and Navy minesweepers began clearing the bay. Engineers of the 38th Division remained in Olongapo to begin reactivation of Subic Bay Naval Station. Bridges, buildings and the water distilling plant were repaired and the beaches and streets were cleared. Soon enough, LSTs were making dry-ramp landings near the town of Subic.

While Army engineers were busy around Subic Bay, the remaining troops moved east along Highway 7, planning to cross the base of Bataan to meet elements of the Army's XIV Corps, which were moving west on the same road. On the morning of 31 January 1945, the Americans began climbing the forested hills of Zig Zag Pass and into a hornet's nest of Japanese.

In the first three days at Zig Zag Pass the U.S. 152nd had more casualties than during 78 days of combat in Leyte. General Henry L. C. Jones was relieved and command of the 38th was given to General Roy W. Easley who used P-47s for air support. The planes began an intensive strafing and bombing of the jungle and dropped napalm on the Japanese positions.

After 15 days of fighting the enemy positions were finally overrun. The Japanese had succeeded in their mission to slow the American advance but lost more than 2,400 troops. American losses had been 1,400 killed.

Subic Bay was designated Naval Advance Unit No. 6, and become a submarine and motor torpedo boat base shortly after the Philippines were liberated. arrived on 11 February 1945 and found Subic Bay " "...a primitive, humid, unhealthy, desolate Siberia far from the pleasant climate, facilities, and girls of Australia..." ". A Naval Supply Depot was established at Maquinaya, about 3 miles (5 km) from the main base in July 1945. A new town of Olongapo was built to replace building burned by the retreating Japanese and provide housing for Filipino civilians employed at the base. Olongapo and its 9,000 Filipino residents remained under United States Navy administration when the remainder of the Philippines became independent on 4 July 1946.
Construction of Naval Air Station Cubi Point began during the Korean War. The town of Banicain was demolished to build the airfield, and its residents were relocated to Olongapo. As Olongapo's population grew to 60,000, Filipinos requested control of the town. On 7 December 1959, 56,000 acres of land with electrical, telephone and water utilities was relinquished to Philippine control. Grande Island was converted to a recreation center for naval personnel; and most of the historic Coastal Artillery guns of Fort Wint were moved to United States coastal defense parks in 1963 and 1968.

The Vietnam War was the period of peak activity as Subic Bay became the U.S. Seventh Fleet forward base for repair and replenishment after the Gulf of Tonkin incident in 1964. The average number of ships visiting the base per month rose from 98 in 1964 to 215 by 1967. The base, with 6 wharves, 2 piers, and 160 mooring points and anchorages, had about 30 ships in port on any given day. Alava pier was extended by in 1967. The record of 47 ships in port was set in October 1968. About one-third of these were Military Sea Transportation Service ships bringing 45,000 tons of food, ammunition, and supplies and 2 million barrels of fuel oil, aviation gasoline, and JP-4 jet fuel each month including fuels transferred to Clark Air Base via a pipeline. The Naval Supply Depot maintained an inventory of 200,000 parts. The 4,224,503 sailors visiting Subic Bay in 1967 purchased more than $25 million in duty-free goods from the Navy Exchange.

More than $63 million of construction projects contracted between 1964 and 1968 did not prepare the Ship Repair Facility (SRF) for the increasing workload and emergency peaks generated by the war. American military and civilian population totaled about 4,300; and more than 15,000 Filipino SRF workers worked 12-hour shifts for an average of over 60 hours per week. The physical plant consisted of quonset huts put up after World War II; and workers used obsolete tools and equipment supplemented by machine tools made available by decommissioning the New York Navy Yard. Additional floating drydocks and a third repair ship were assigned from the United States to increase the capabilities of the repair facility.

The fire-ravaged was repaired in August 1967 before her return to the United States for a complete overhaul. Destroyers,, and, damaged by North Vietnamese shore batteries, were repaired, as were amphibious assault craft, river patrol boats and other small craft.

The Royal Australian Navy destroyer was repaired at Subic following the attack by USAF aircraft on 17 June 1968.
On 3 June 1969 the Royal Australian Navy carrier was involved in a collision with about southwest of Manila. brought 196 of the 199 survivors to Subic Bay. A Joint Australian/U.S. Board of Inquiry convened on 9 June in the library of George Dewey High School, the same day the stern section of "Frank E. Evans" arrived under tow by a tug. It was stripped and towed to sea as a gunnery target.

Harbor Clearance Unit One was activated at Subic Bay in 1966 with the mission of salvaging ships from the rivers and harbors of Vietnam. Two of the biggest jobs were the salvaging of "SS Baton Rouge Victory" from the Saigon River and the raising of the dredge "Jamaica Bay" from the Mỹ Tho River. Both jobs were accomplished despite continuous harassment by enemy sniper fire.

NAS Cubi Point served as the primary maintenance, repair and supply center for the 400 carrier based aircraft of the Seventh Fleet's carrier force. The jet engine shop turned out two jet engines a day to keep pace with the demands of the air war in Vietnam.
Following the Fall of Saigon in the summer of 1975 hundreds of thousands of refugees fled Vietnam. Thousands of these refugees were rescued at sea by U.S. Navy ships and taken to Subic Bay. A temporary processing center that handled thousands of refugees was set up on Grande Island in 1975. They were later taken to the Philippine Refugee Processing Center in Morong, Bataan.

The Military Bases Agreement of 1947 was amended in 1979, changing the role of the Americans at Subic Bay from landlord to guest. The amendment confirmed Philippine sovereignty over the base and reduced the area set aside for U.S. use from to. Philippine troops assumed responsibility for the perimeter security of the base to reduce incidents between U.S. military and Philippine civilians. The unhampered operation of U.S. forces was assured. The U.S. granted the Philippines $500 million in military sales credits and supporting assistance.

On 15 June 1991, Mount Pinatubo, just 20 miles (32 km) from Subic Bay, exploded with a force eight times greater than the Mount St. Helens eruption. The sun was nearly completely hidden as volcanic ash blotted it out. Volcanic earthquakes and heavy rain, lightning and thunder from Typhoon "Yunya" passing over northern Luzon resulted in a 36-hour period of complete chaos.

By the morning of 16 June, when the eruption subsided, Subic Bay lay buried under of rain-soaked, sandy ash.

Buildings everywhere collapsed under the weight of the coarse gray ash. Two girls, one a nine-year-old American and the other a Filipino citizen, died when trapped under a falling roof at George Dewey High School. In the city of Olongapo, more than 60 volcano-related deaths were reported, including eight who were crushed when part of Olongapo General Hospital collapsed.
That night, the threat of continued eruptions combined with the lack of water and electricity led to the decision to evacuate all dependents. U.S. warships and cargo planes began the emergency evacuation of thousands of Navy and Air Force dependents. Seven Navy ships sailed Monday, 17 June, with 6,200 dependents. A total of 17 ships, including the aircraft carriers, and evacuated all 20,000 dependents over the next few days. The evacuees were taken by ship to Mactan Air Base and then were airlifted by U.S. Air Force C-141 Starlifters to Andersen Air Force Base at Guam. After the dependents were evacuated, an intense clean-up was begun. All hands, American service members and Filipino base employees, worked around the clock to restore essential services. Clark Air Base, much closer to Mount Pinatubo, was covered with tons of ash after the eruption. It was declared a total loss and plans for a complete closure were started.

Within two weeks NAS Cubi Point was back in limited operation. Soon, most buildings had electricity and water restored. By mid-July service had been restored to most family housing units. The dependents began returning 8 September 1991 and by the end of the month almost all were back at Subic Bay from the United States. In September 1991, more than twenty thousand Filipino civilians were employed by the base.

From 1988 to 1992, the US Government and Philippine government tried to renegotiate the terms of an extension of the military bases at Subic and Clark. This referred to the Military Bases Agreement of 1947, which was due to expire. Intense negotiations between the governments of the United States and the Philippines began. These negotiations resulted in the Treaty of Friendship, Peace and Cooperation between the United States and the Republic of the Philippines. This would have extended the lease of the American bases in the Philippines. However, a bone of contention remained the amount of money that the US Government would pay to the Philippine government for the lease and use of the bases.

As per C.R.Anderegg, the Vice Commander of Clark Air Base, Philippines wanted $825 million per year for a period of seven years, but the U.S. Government wouldn't budge from the earlier agreed $360 million per year for 10 years. This was not the first such hike demanded by the Philippines - in 1984, a similar hike had been asked and given for Clark Air Base. However, this time, the US government did not agree.

On 13 September 1991, the Philippine Senate rejected the ratification of this treaty.

In December 1991, the two governments were again in talks to extend the withdrawal of American forces for three years but this broke down as the United States refused to detail their withdrawal plans or to answer if nuclear weapons were kept on base. Additionally, the United States offered only one quarter of the $825 million in rent sought by the Filipino Government. Finally on 27 December, President Corazon Aquino, who had previously fought to delay the U.S. pullout to cushion the country's battered economy, issued a formal notice for the U.S. to leave by the end of 1992. Naval Station Subic Bay was the U.S.'s largest overseas defense facility after Clark Air Base was closed.

In 1992, tons of materiel including drydocks and equipment, were shipped to various Naval Stations. Ship repair, maintenance yards and supply depots were relocated to other Asian countries including Japan and Singapore. On 24 November 1992, the American Flag was lowered in Subic for the last time and the last 1,416 Sailors and Marines at Subic Bay Naval Base left by plane from Naval Air Station Cubi Point and by. This withdrawal marked the first time since the 16th century that no foreign military forces were present in the Philippines. The departure of the United States Navy left a huge clean-up to be completed. Soil and water was contaminated with lead, asbestos, PCBs, pesticides, and possibly nuclear waste from submarines. As of 2012, clean-up estimates for Subic Bay Naval Base and Clark Air Base were $40 million each.

Beginning in June 2012, the Philippine government said that the United States military could use the old base with prior approval by the Philippine government. This follows expanded military ties between the two nations, and an American pivot towards Asia. This follows a Visiting Forces Agreement made in 1999, that saw annual visits of United States forces to conduct large scale exercises (known as Balikatan) between the two allies. "The Sydney Morning Herald" reported on 20 November 2012 that Subic Bay will host US ships, Marines and aircraft on a semi-permanent basis which according to analysts will give the US a strategically important force posture for its shift in emphasis to the Pacific.

The US Navy began using the base in Subic Bay in 2015 to deliver materiel and personnel for annual joint military exercises. Some 6,000 US personnel came to Subic in April, and returned for exercises in 2016 in agreement with Philippine authorities. US ships have used Subic Bay as a resupply port during routine calls.

"Other former United States Navy installations:"


How many mammary glands do human women have?

All the milk-secreting tissue leading to a single lactiferous duct is called a "simple mammary gland"; in a "complex mammary gland" all the simple mammary glands serve one nipple. Humans normally have two complex mammary glands, one in each breast, and each complex mammary gland consists of 10–20 simple glands. The presence of more than two nipples is known as polythelia and the presence of more than two complex mammary glands as polymastia.

Mammary gland

A mammary gland is an exocrine gland in mammals that produces milk to feed young offspring. Mammals get their name from the Latin word "mamma", "breast". The mammary glands are arranged in organs such as the breasts in primates (for example, humans and chimpanzees), the udder in ruminants (for example, cows, goats, and deer), and the dugs of other animals (for example, dogs and cats). Lactorrhea, the occasional production of milk by the glands, can occur in any mammal, but in most mammals, lactation, the production of enough milk for nursing, occurs only in phenotypic females who have gestated in recent months or years. It is directed by hormonal guidance from sex steroids. In a few mammalian species, male lactation can occur.

The basic components of a mature mammary gland are the "alveoli" (hollow cavities, a few millimeters large) lined with milk-secreting cuboidal cells and surrounded by myoepithelial cells. These alveoli join to form groups known as "lobules". Each lobule has a "lactiferous duct" that drains into openings in the nipple. The myoepithelial cells contract under the stimulation of oxytocin, excreting the milk secreted by alveolar units into the lobule lumen toward the nipple. As the infant begins to suck, the oxytocin-mediated "let down reflex" ensues and the mother's milk is secreted — not sucked from the gland — into the baby's mouth.

Maintaining the correct polarized morphology of the lactiferous duct tree requires another essential component – mammary epithelial cells extracellular matrix (ECM) which, together with adipocytes, fibroblast, inflammatory cells, and others, constitute mammary stroma. Mammary epithelial ECM mainly contains myoepithelial basement membrane and the connective tissue. They not only help to support mammary basic structure, but also serve as a communicating bridge between mammary epithelia and their local and global environment throughout this organ's development.

A mammary gland is a specific type of apocrine gland specialized for manufacture of colostrum when giving birth. Mammary glands can be identified as apocrine because they exhibit striking "decapitation" secretion. Many sources assert that mammary glands are modified sweat glands. Some authors dispute that and argue instead that they are sebaceous glands.

Mammary glands develop during different growth cycles. They exist in both sexes during embryonic stage, forming only a rudimentary duct tree at birth. In this stage, mammary gland development depends on systemic (and maternal) hormones, but is also under the (local) regulation of paracrine communication between neighboring epithelial and mesenchymal cells by parathyroid hormone-related protein (PTHrP). This locally secreted factor gives rise to a series of outside-in and inside-out positive feedback between these two types of cells, so that mammary bud epithelial cells can proliferate and sprout down into the mesenchymal layer until they reach the fat pad to begin the first round of branching. At the same time, the embryonic mesenchymal cells around the epithelial bud receive secreting factors activated by PTHrP, such as BMP4. These mesenchymal cells can transform into a dense, mammary-specific mesenchyme, which later develop into connective tissue with fibrous threads, forming blood vessels and the lymph system. A basement membrane, mainly containing laminin and collagen, formed afterward by differentiated myoepithelial cells, keeps the polarity of this primary duct tree. These components of the extracellular matrix are strong determinants of duct morphogenesis.

Estrogen and growth hormone (GH) are essential for the ductal component of mammary gland development, and act synergistically to mediate it. Neither estrogen nor GH are capable of inducing ductal development without the other. The role of GH in ductal development has been found to be mostly mediated by its induction of the secretion of insulin-like growth factor 1 (IGF-1), which occurs both systemically (mainly originating from the liver) and locally in the mammary fat pad through activation of the growth hormone receptor (GHR). However, GH itself also acts independently of IGF-1 to stimulate ductal development by upregulating estrogen receptor (ER) expression in mammary gland tissue, which is a downstream effect of mammary gland GHR activation. In any case, unlike IGF-1, GH itself is not essential for mammary gland development, and IGF-1 in conjunction with estrogen can induce normal mammary gland development without the presence of GH. In addition to IGF-1, other paracrine growth factors such as epidermal growth factor (EGF), transforming growth factor beta (TGF-β), amphiregulin, fibroblast growth factor (FGF), and hepatocyte growth factor (HGF) are involved in breast development as mediators downstream to sex hormones and GH/IGF-1.

During embryonic development, IGF-1 levels are low, and gradually increase from birth to puberty. At puberty, the levels of GH and IGF-1 reach their highest levels in life and estrogen begins to be secreted in high amounts in females, which is when ductal development mostly takes place. Under the influence of estrogen, stromal and fat tissue surrounding the ductal system in the mammary glands also grows. After puberty, GH and IGF-1 levels progressively decrease, which limits further development until pregnancy, if it occurs. During pregnancy, progesterone and prolactin are essential for mediating lobuloalveolar development in estrogen-primed mammary gland tissue, which occurs in preparation of lactation and nursing.

Androgens such as testosterone inhibit estrogen-mediated mammary gland development (e.g., by reducing local ER expression) through activation of androgen receptors expressed in mammary gland tissue, and in conjunction with relatively low estrogen levels, are the cause of the lack of developed mammary glands in males.

Mammary gland development is characterized by the unique process by which the epithelium invades the stroma. The development of the mammary gland occurs mainly after birth. During puberty, tubule formation is coupled with branching morphogenesis which establishes the basic arboreal network of ducts emanating from the nipple.

Developmentally, mammary gland epithelium is constantly produced and maintained by rare epithelial cells, dubbed as mammary progenitors which are ultimately thought to be derived from tissue-resident stem cells.

Embryonic mammary gland development can be divided into a series of specific stages. Initially, the formation of the milk lines that run between the fore and hind limbs bilaterally on each side of the midline occurs around embryonic day 10.5 (E10.5). The second stage occurs at E11.5 when placode formation begins along the mammary milk line. This will eventually give rise to the nipple. Lastly, the third stage occurs at E12.5 and involves the invagination of cells within the placode into the mesenchyme, leading to a mammary anlage (biology).

The primitive (stem) cells are detected in embryo and their numbers increase steadily during development

Postnatally, the mammary ducts elongate into the mammary fat pad. Then, starting around four weeks of age, mammary ductal growth increases significantly with the ducts invading towards the lymph node. Terminal end buds, the highly proliferative structures found at the tips of the invading ducts, expand and increase greatly during this stage. This developmental period is characterized by the emergence of the terminal end buds and lasts until an age of about 7–8 weeks.

By the pubertal stage, the mammary ducts have invaded to the end of the mammary fat pad. At this point, the terminal end buds become less proliferative and decrease in size. Side branches form from the primary ducts and begin to fill the mammary fat pad. Ductal development decreases with the arrival of sexual maturity and undergoes estrous cycles (proestrus, estrus, metestrus, and diestrus). As a result of estrous cycling, the mammary gland undergoes dynamic changes where cells proliferate and then regress in an ordered fashion.

During pregnancy, the ductal systems undergo rapid proliferation and form alveolar structures within the branches to be used for milk production. After delivery, lactation occurs within the mammary gland; lactation involves the secretion of milk by the luminal cells in the alveoli. Contraction of the myoepithelial cells surrounding the alveoli will cause the milk to be ejected through the ducts and into the nipple for the nursing infant. Upon weaning of the infant, lactation stops and the mammary gland turns in on itself, a process called "involution". This process involves the controlled collapse of mammary epithelial cells where cells begin apoptosis in a controlled manner, reverting the mammary gland back to a pubertal state.

During postmenopause, due to much lower levels of estrogen, and due to lower levels of GH and IGF-1, which decrease with age, mammary gland tissue atrophies and the mammary glands become smaller.

Lactiferous duct development occurs in females in response to circulating hormones. First development is frequently seen during pre- and postnatal stages, and later during puberty. Estrogen promotes branching differentiation, whereas in males testosterone inhibits it. A mature duct tree reaching the limit of the fat pad of the mammary gland comes into being by bifurcation of duct terminal end buds (TEB), secondary branches sprouting from primary ducts and proper duct lumen formation. These processes are tightly modulated by components of mammary epithelial ECM interacting with systemic hormones and local secreting factors. However, for each mechanism the epithelial cells' "niche" can be delicately unique with different membrane receptor profiles and basement membrane thickness from specific branching area to area, so as to regulate cell growth or differentiation sub-locally. Important players include beta-1 integrin, epidermal growth factor receptor (EGFR), laminin-1/5, collagen-IV, matrix metalloproteinase(MMPs), heparan sulfate proteoglycans, and others. Elevated circulating level of growth hormone and estrogen get to multipotent cap cells on TEB tips through a thin, leaky layer of basement membrane. These hormones promote specific gene expression. Hence cap cells can differentiate into myoepithelial and luminal (duct) epithelial cells, and the increased amount of activated MMPs can degrade surrounding ECM helping duct buds to reach further in the fat pads. On the other hand, basement membrane along the mature mammary ducts is thicker, with strong adhesion to epithelial cells via binding to integrin and non-integrin receptors. When side branches develop, it is a much more “pushing-forward” working process including extending through myoepithelial cells, degrading basement membrane and then invading into a periductal layer of fibrous stromal tissue. Degraded basement membrane fragments (laminin-5) roles to lead the way of mammary epithelial cells migration. Whereas, laminin-1 interacts with non-integrin receptor dystroglycan negatively regulates this side branching process in case of cancer. These complex "Yin-yang" balancing crosstalks between mammary ECM and epithelial cells "instruct" healthy mammary gland development until adult.

There is preliminary evidence that soybean intake mildly stimulates the breast glands in pre- and postmenopausal women.

Secretory alveoli develop mainly in pregnancy, when rising levels of prolactin, estrogen, and progesterone cause further branching, together with an increase in adipose tissue and a richer blood flow. In gestation, serum progesterone remains at a stably high concentration so signaling through its receptor is continuously activated. As one of the transcribed genes, Wnts secreted from mammary epithelial cells act paracrinely to induce more neighboring cells' branching. When the lactiferous duct tree is almost ready, "leaves" alveoli are differentiated from luminal epithelial cells and added at the end of each branch. In late pregnancy and for the first few days after giving birth, colostrum is secreted. Milk secretion (lactation) begins a few days later due to reduction in circulating progesterone and the presence of another important hormone prolactin, which mediates further alveologenesis, milk protein production, and regulates osmotic balance and tight junction function. Laminin and collagen in myoepithelial basement membrane interacting with beta-1 integrin on epithelial surface again, is essential in this process. Their binding ensures correct placement of prolactin receptors on the basal lateral side of alveoli cells and directional secretion of milk into lactiferous ducts. Suckling of the baby causes release of the hormone oxytocin, which stimulates contraction of the myoepithelial cells. In this combined control from ECM and systemic hormones, milk secretion can be reciprocally amplified so as to provide enough nutrition for the baby.

During weaning, decreased prolactin, missing mechanical stimulation (baby suckling), and changes in osmotic balance caused by milk stasis and leaking of tight junctions cause cessation of milk production. It is the (passive) process of a child or animal ceasing to be dependent on the mother for nourishment. In some species there is complete or partial involution of alveolar structures after weaning, in humans there is only partial involution and the level of involution in humans appears to be highly individual. The glands in the breast do secrete fluid also in nonlactating women. In some other species (such as cows), all alveoli and secretory duct structures collapse by programmed cell death (apoptosis) and autophagy for lack of growth promoting factors either from the ECM or circulating hormones. At the same time, apoptosis of blood capillary endothelial cells speeds up the regression of lactation ductal beds. Shrinkage of the mammary duct tree and ECM remodeling by various proteinase is under the control of somatostatin and other growth inhibiting hormones and local factors. This major structural change leads loose fat tissue to fill the empty space afterward. But a functional lactiferous duct tree can be formed again when a female is pregnant again.

Tumorigenesis in mammary glands can be induced biochemically by abnormal expression level of circulating hormones or local ECM components, or from a mechanical change in the tension of mammary stroma. Under either of the two circumstances, mammary epithelial cells would grow out of control and eventually result in cancer. Almost all instances of breast cancer originate in the lobules or ducts of the mammary glands.

The breasts of the adult human female vary from most other mammals that tend to have less conspicuous mammary glands. The number and positioning of mammary glands varies widely in different mammals. The protruding teats and accompanying glands can be located anywhere along the two milk lines. In general most mammals develop mammary glands in pairs along these lines, with a number approximating the number of young typically birthed at a time. The number of teats varies from 2 (in most primates) to 18 (in pigs). The Virginia opossum has 13, one of the few mammals with an odd number. The following table lists the number and position of teats and glands found in a range of mammals:

Male mammals typically have rudimentary mammary glands and nipples, with a few exceptions: male mice do not have nipples, and male horses lack nipples and mammary glands. The male Dayak fruit bat has lactating mammary glands. Male lactation occurs infrequently in some species, including humans.

Mammary glands are true protein factories, and several labs have constructed transgenic animals, mainly goats and cows, to produce proteins for pharmaceutical use. Complex glycoproteins such as monoclonal antibodies or antithrombin cannot be produced by genetically engineered bacteria, and the production in live mammals is much cheaper than the use of mammalian cell cultures.

The evolution of the mammary gland is difficult to explain; this is because mammary glands are typically required by mammals to feed their young. There are many theories on how mammary glands evolved. For example, it is thought that the mammary gland is a transformed sweat gland, more closely related to apocrine sweat glands. Because mammary glands do not fossilize well, supporting such theories with fossil evidence is difficult. Many of the current theories are based on comparisons between lines of living mammals—monotremes, marsupials, and eutherians. One theory proposes that mammary glands evolved from glands that were used to keep the eggs of early mammals moist and free from infection (monotremes still lay eggs). Other theories suggest that early secretions were used directly by hatched young, or that the secretions were used by young to help them orient to their mothers.

Lactation is thought to have developed long before the evolution of the mammary gland and mammals; see evolution of lactation.

A distinguishing characteristic of the class "Mammalia" is the presence of mammary glands. The mammary glands are modified sweat glands that produce milk, which is used to feed the young for some time after birth. Only mammals produce milk. Mammary glands are most obvious in humans, as the female human body stores large amounts of fatty tissue near the nipples, resulting in prominent breasts. Mammary glands are present in all mammals, although they are seldom used by the males of the species.

Female

Female (♀) is the sex of an organism, or a part of an organism, that produces non-mobile ova (egg cells). Barring rare medical conditions, most female mammals, including female humans, have two X chromosomes. Female characteristics vary between different species with some species containing more well defined female characteristics. Both genetics and environment shape the prenatal development of a female.

The ova are defined as the larger gametes in a heterogamous reproduction system, while the smaller, usually motile gamete, the spermatozoon, is produced by the male. A female individual cannot reproduce sexually without access to the gametes of a male, and vice versa. Some organisms can also reproduce by themselves in a process known as asexual reproduction. An example of asexual reproduction that some female species can perform is parthenogenesis.

There is no single genetic mechanism behind sex differences in different species and the existence of two sexes seems to have evolved multiple times independently in different evolutionary lineages. Patterns of sexual reproduction include

Other than the defining difference in the type of gamete produced, differences between males and females in one lineage cannot always be predicted by differences in another. The concept is not limited to animals; egg cells are produced by chytrids, diatoms, water moulds and land plants, among others. In land plants, "female" and "male" designate not only the egg- and sperm-producing organisms and structures, but also the structures of the sporophytes that give rise to male and female plants.

The word "female" comes from the Latin "femella", the diminutive form of "femina", meaning "woman". It is not etymologically related to the word "male", but in the late 14th century the spelling was altered in English to parallel the spelling of "male".

Most mammalian females have two copies of the X chromosome as opposed to the male which carries only one X and one smaller Y chromosome (but some mammals, such as the platypus, have different combinations). To compensate for the difference in size, one of the female's X chromosomes is randomly inactivated in each cell of placental mammals while the paternally derived X is inactivated in marsupials. In birds and some reptiles, by contrast, it is the female which is heterozygous and carries a Z and a W chromosome whilst the male carries two Z chromosomes. Intersex conditions can also give rise to other combinations, such as XO or XXX in mammals, which are still considered as female so long as they do not contain a Y chromosome, except for specific cases of testosterone deficiency/insensitivity in XY individuals while in the womb. However, these conditions frequently result in sterility.

Mammalian females bear live young (with the rare exception of monotremes, which lay eggs). Some non-mammalian species, such as guppies, have analogous reproductive structures; and some other non-mammals, such as sharks, whose eggs hatch inside their bodies, also have the appearance of bearing live young.

A common symbol used to represent the female sex is ♀ (Unicode: U+2640 Alt codes: Alt+12), a circle with a small cross underneath. According to Schott, the most established view is that the male and female symbols "are derived from contractions in Greek script of the Greek names of these planets, namely Thouros (Mars) and Phosphoros (Venus). These derivations have been traced by Renkama who illustrated how Greek letters can be transformed into the graphic male and female symbols still recognised today." Thouros was abbreviated by θρ, and Phosphoros by Φ, both in the handwriting of alchemists so somewhat different from the Greek symbols we know. These abbreviations were contracted into the modern symbols.

The sex of a particular organism may be determined by a number of factors. These may be genetic or environmental, or may naturally change during the course of an organism's life. Although most species with male and female sexes have individuals that are either male or female, hermaphroditic animals have both male and female reproductive organs.

The sex of most mammals, including humans, is genetically determined by the XY sex-determination system where males have X and Y (as opposed to X and X) sex chromosomes. During reproduction, the male contributes either an X sperm or a Y sperm, while the female always contributes an X egg. A Y sperm and an X egg produce a male, while an X sperm and an X egg produce a female. The ZW sex-determination system, where males have ZZ (as opposed to ZW) sex chromosomes, is found in birds, reptiles and some insects and other organisms. Members of Hymenoptera, such as ants and bees, are determined by haplodiploidy, where most males are haploid and females and some sterile males are diploid.

The young of some species develop into one sex or the other depending on local environmental conditions, e.g. many crocodilians' sex is influenced by the temperature of their eggs. Other species (such as the goby) can transform, as adults, from one sex to the other in response to local reproductive conditions (such as a brief shortage of males).Ayers, Donald M. "English Words from Latin and Greek Elements". Second Edition. 1986. University of Arizona Press. United States.