where is the small intestine located in a fetal pig

The monogastric digestive system of the fetal pig harbors many similarities with many other mammals. The fetal pig's digestive organs are well developed before birth, although it does not ingest food. These organs include the esophagus, stomach, small and large intestines. Mesenteries serve to connect the organs of the fetal pig together. In order for digestion to occur, the fetal pig would have to ingest food. Instead, it gains much needed nutrition from the mother pig via the umbilical cord. In the adult pig, food will follow the general flow through the esophagus, which can be located behind the tracheae. From the oral cavity, the esophagus leads to the stomach, small intestine, and large intestine. Other organs developing during fetal pig development such as the gallbladder, pancreas and spleen are all critical in contributing to the overall flow of the digestive system because they contain digestive enzymes that will perform chemical digestion of food. After food is digested and nutrients are absorbed, the food follows through the large intestine and solid wastes are excreted through the anus. In the fetal pig however, the metabolic wastes are sent back to the mother through the umbilical cord where the mother excretes the wastes. Other remaining wastes remain in the fetal pig until birth. Then

Fetal pig

Fetal pigs are unborn pigs used in elementary as well as advanced biology classes as objects for dissection. Pigs, as a mammalian species, provide a good specimen for the study of physiological systems and processes due to the similarities between many pig and human organs.

Along with frogs and earthworms, fetal pigs are among the most common animals used in classroom dissection. There are several reasons for this, the main reason being that pigs, like humans, are mammals. Shared traits include common hair, mammary glands, live birth, similar organ systems, metabolic levels, and basic body form. They also allow for the study of fetal circulation, which differs from that of an adult. Secondly, fetal pigs are easy to obtain because they are by-products of the pork industry. Fetal pigs are the unborn piglets of sows that were killed by the meat packing industry. These pigs are not bred and killed for this purpose, but are extracted from the deceased sowâ€™s uterus. Fetal pigs not used in classroom dissections are often used in fertilizer or simply discarded.[1] Thirdly, fetal pigs are cheap, which is an essential component for dissection use by schools. They can be ordered for a little more than $25 at biological product companies. Fourthly, fetal pigs are easy to dissect because of their soft tissue and incompletely developed bones that are still made of cartilage.[2] In addition, they are relatively large with well-developed organs that are easily visible. As long as the pork industry exists, fetal pigs will be relatively abundant, making them the prime choice for classroom dissections.

Several peer-reviewed comparative studies have concluded that the educational outcomes of students who are taught basic and advanced biomedical concepts and skills using non-animal methods are equivalent or superior to those of their peers who use animal-based laboratories such as animal dissection.[3][4]

A systematic review concluded that students taught using non-animal methods demonstrated “superior understanding of complex biological processes, increased learning efficiency, and increased examination results.” [5] It also reported that students’ confidence and satisfaction increased as did their preparedness for laboratories and their information-retrieval and communication abilities.[6]

Three studies at universities across the United States found that students who modeled body systems out of clay were significantly better at identifying the constituent parts of human anatomy than their classmates who performed animal dissection.[7][8][9]

Another study found that students preferred using clay modeling over animal dissection and performed just as well as their cohorts who dissected animals.[10]

The size of the fetal pig depends on the time allowed for the mother to gestate:

No studies have found significant data regarding the mother swineâ€™s diet and fetal pig survival rate. However, there is a correlation between a mother pig having a nutritious diet containing proteins, vitamins and minerals during gestation period and the survival rate of piglets. The correlation, however, is not statistically different. Weight is also not a factor of survival rate because a healthier diet does not lead to a heavier offspring or a greater chance of live birth.[11]

The placenta is used as a means of transferring nutrients from the mother to the fetus. The efficiency at which nutrients are transferred dictates the health and growth of the fetus. FRP, or fetal weight: placental weight ratio, was commonly used to determine placental efficiency. However, increasing FPR does not prove to increase litter size. Instead, a more accurate way of determining fetus growth is through certain characteristics of the placental lining. The placenta is made of a folded trophoblast/endometrial epithelial bilayer. The width and length of the placenta folds are positively related and increase as gestation progresses.

The width of the placental folds decreases until day 85 of gestation. From here, the width increases with gestation and is at its largest around day 105. The rate at which these folds increase is negatively related to fetus size. Thus, greater fold widths will be seen in smaller fetuses. Although increasing placental fold width does increase the interaction between fetus and mother, nutrient exchange is not most efficient in smaller fetal pigs, as would be expected. Many other factors, including depth of placental folds, are also responsible for these interactions.[12]

The prenatal development of the fetus includes all the tissue and organ development. Within hours of mating, the sperm and egg undergo fertilization in the oviduct and three days later the egg moves into the uterus. The cells begin to specialize by day six, and attach themselves to the uterus lining by day eleven. From fertilization to day 18, the endoderm, ectoderm and mesoderm have been forming inside the embryo, and are completely formed by day 18, the same day the placenta forms. The endoderm transforms into the lungs, trachea, thyroid gland, and digestive tract of the fetus. The ectoderm has a greater role in the development of the fetus. It forms into the skin, nervous system, enamel of the teeth, lining of the intestine, mammary and sweat glands, hoofs, and hair. The mesoderm forms the major organ components that help keep the fetus alive. It forms the muscles and connective tissues of the body, blood vessels and cells, the skeleton, kidneys, adrenal glands, heart, and the reproductive organs. By day 20, most of the major organs are visible, and the last half of gestation focuses greatly on increasing the size of the fetuses.[13]

The development of the lymphatic system and the formation of blood circulation occur at different stages of fetal pig development. The first lymphatic organ to become present is the thymus. Lymphocyte builds up in the spleen on the 70th day. By day 77, the thymus is already completely developed and is distinguishable from other organs. Also, follicles are present on the tongue and intestines on day 77. On the 84th day, Periarteriolar lymphoid sheaths appear in the fetal pig. By this time, the liver and bone marrow are active and functional.[14]

Studies have shown that litter size, the amount of floor space during the growing period, and the number of pigs the gilt, or female pig, is placed with while growing affect the reproduction rates of the gilts. Data from a study in 1976 by Nelson and Robinson showed that gilts from a small litter size ovulated more than the gilts from the larger litters. The study suggests stress plays a role in impacting the reproduction. The amount of floor space has been shown to impact the time it takes gilts to reach puberty. An adequate amount of floor space allowed the higher percentage of gilts to reach puberty sooner than those gilts who had less floor space. The gilts placed in smaller groups bore one more pig per litter than gilts in larger groups. Still, the environment in which the fetal gilt develops is significant to the reproductive and physiological development.[15] Author: Brandon Anderson

Fetal pigs are often preserved in formaldehyde[citation needed], a carcinogenic substance. A 1980 study found that exposure to formaldehyde could possibly cause nasal cancer in rats, leading to research on whether this was possible in humans or not.[16] In 1995 it was concluded by the International Agency for Research on Cancer (IARC) that formaldehyde is a carcinogen for humans.[17] In Albania, fetal pigs are preserved by means of alcohol, and are used as an ingredient in Raki, a local moonshine liquor.[18]

The anatomy of a fetal pig is similar to that of the adult pig in various aspects. Systems that are similar include the nervous, skeletal, respiratory (neglecting the under developed diaphragm), and muscular. Other important body systems have significant differences from the adult pig.

There are only a few differences between the circulatory system of an adult pig and a fetal pig, besides from the umbilical arteries and vein. There is a shunt between the wall of the right and left atrium called the foramen ovale. This allows blood to pass directly from the right to left atrium. There is also the ductus arterius which allows blood from the right atrium to be diverted to the aortic arch. Both of these shunts close a few minutes after birth.

The oral cavity of the fetal pig begins developing before birth. The tongue's taste buds, located in the enlarged papillae, facilitate food handling after birth. These taste buds develop during fetal development. Adult pigs have up to 15,000 taste buds, a much larger number than the average human tongue, which has 9,000.[19]

The dental anatomy of the fetal pig shows differences from adult pigs. The fetal pig develops primary teeth (which are later replaced with permanent teeth). Some may erupt during fetal stage, which is why some of the fetuses show evidence of teeth. Depending on the age of the fetal pig, it is natural to see eruptions of third incisor and canine in the fetal pig.[20] Because the fetal pigs were still in the motherâ€™s uterus, teeth will still form which supports reasons for hollow unerupted teeth that may be seen. Similar to human dental anatomy, the overall dental anatomy of the pig consists of incisors, canines, pre-molars, and molars. Piglets can have 28 teeth total and adult pigs can have 44 teeth total.[21]

The fetal pig's urogenital system is similar to the adult pig's system with the exception of the reproductive organs. The fetal pig urinary tract is relatively developed and easy to locate during dissection. The kidneys are located behind the abdominal organs and are partially embedded into the dorsal body wall by the spine. The ureters carry the urine to the urinary bladder, the large sack-like organ by the umbilical artery and vein, to the urethra. From there, the urine can be excreted.

If the fetal pig is a female, there will be a fleshy protrusion ventral near the anus called the genital papilla.[22] The female's internal reproductive system is located below the kidneys. The two sac-like organs attached to the coil-like fallopian tubes are the ovaries.[23] The uterus, which becomes the vagina, is located where the fallopian tubes meet. This system can be difficult to find as it is small as well as extremely dorsal and posterior to the other systems.

Male fetal pigs have an urogenital opening located behind the umbilical cord. The swelling behind the hind legs of the fetal pig[24] is the scrotum. The male's internal reproductive system has two scrotal sacs, which depending on the age of the fetal pig may or may not have developed testes.[25] The epididymis coil on the testes connects to the vas deferens. The vas deferens crosses over the ureter and enters the urethra, which then connects to the penis located just posterior to the skin.[26] Similar to the female system, it may be difficult to identify all parts.


bob dylan blowin in the wind original version

"Blowin' in the Wind" is a song written by Bob Dylan in 1962 and released as a single and on his album The Freewheelin' Bob Dylan in 1963. Although it has been described as a protest song, it poses a series of rhetorical questions about peace, war, and freedom. The refrain "The answer, my friend, is blowin' in the wind" has been described as "impenetrably ambiguous: either the answer is so obvious it is right in your face, or the answer is as intangible as the wind".[2]

Blowin' in the Wind

In 1994, the song was inducted into the Grammy Hall of Fame. In 2004, it was ranked number 14 on Rolling Stone magazine's list of the "500 Greatest Songs of All Time".

Dylan originally wrote and performed a two-verse version of the song; its first public performance, at Gerde's Folk City on April 16, 1962, was recorded and circulated among Dylan collectors. Shortly after this performance, he added the middle verse to the song. Some published versions of the lyrics reverse the order of the second and third verses, apparently because Dylan simply appended the middle verse to his original manuscript, rather than writing out a new copy with the verses in proper order.[3] The song was published for the first time in May 1962, in the sixth issue of Broadside, the magazine founded by Pete Seeger and devoted to topical songs.[4] The theme may have been taken from a passage in Woody Guthrie's autobiography, Bound for Glory, in which Guthrie compared his political sensibility to newspapers blowing in the winds of New York City streets and alleys. Dylan was certainly familiar with Guthrie's work; his reading of it had been a major turning point in his intellectual and political development.[5]

In June 1962, the song was published in Sing Out!, accompanied by Dylan's comments:

There ain’t too much I can say about this song except that the answer is blowing in the wind. It ain't in no book or movie or TV show or discussion group. Man, it's in the wind — and it’s blowing in the wind. Too many of these hip people are telling me where the answer is but oh I won't believe that. I still say it's in the wind and just like a restless piece of paper it's got to come down some ... But the only trouble is that no one picks up the answer when it comes down so not too many people get to see and know ... and then it flies away. I still say that some of the biggest criminals are those that turn their heads away when they see wrong and know it's wrong. I'm only 21 years old and I know that there's been too many ... You people over 21, you're older and smarter.[6]

Dylan recorded "Blowin' in the Wind" on July 9, 1962, for inclusion on his second album, The Freewheelin' Bob Dylan, released in May 1963.

In his sleeve notes for The Bootleg Series Volumes 1–3 (Rare & Unreleased) 1961–1991, John Bauldie wrote that Pete Seeger first identified the melody of "Blowin' in the Wind" as an adaptation of the old African-American spiritual "No More Auction Block/We Shall Overcome". According to Alan Lomax's The Folk Songs of North America, the song originated in Canada and was sung by former slaves who fled there after Britain abolished slavery in 1833. In 1978, Dylan acknowledged the source when he told journalist Marc Rowland: "'Blowin' in the Wind' has always been a spiritual. I took it off a song called 'No More Auction Block' – that's a spiritual and 'Blowin' in the Wind' follows the same feeling."[7] Dylan's performance of "No More Auction Block" was recorded at the Gaslight Cafe in October 1962, and appeared on The Bootleg Series Volumes 1–3 (Rare & Unreleased) 1961–1991.

The critic Michael Gray suggested that the lyric is an example of Dylan's incorporation of Biblical rhetoric into his own style. A particular rhetorical form deployed time and again in the New Testament and based on a text from the Old Testament book of Ezekiel (12:1–2) is: "The word of the Lord came to me: 'Oh mortal, you dwell among the rebellious breed. They have eyes to see but see not; ears to hear, but hear not." In "Blowin' in the Wind", Dylan transforms this into "Yes'n' how many ears must one man have ...?" and "Yes' n' how many times must a man turn his head / Pretending he just doesn't see?"[8]

"Blowin' in the Wind" has been described as an anthem of the civil rights movement.[9] In Martin Scorsese's documentary on Dylan, No Direction Home, Mavis Staples expressed her astonishment on first hearing the song and said she could not understand how a young white man could write something that captured the frustration and aspirations of black people so powerfully. Sam Cooke was similarly deeply impressed by the song, incorporating it into his repertoire soon after its release (a version would be included on Sam Cooke at the Copa), and being inspired by it to write "A Change Is Gonna Come".[10][11]

"Blowin' in the Wind" was first covered by The Chad Mitchell Trio, but their record company delayed release of the album containing it because the song included the word death, so the trio lost out to Peter, Paul and Mary, who were represented by Dylan's manager, Albert Grossman. The single sold a phenomenal 300,000 copies in the first week of release and made the song world-famous. On August 17, 1963, it reached number two on the Billboard pop chart, with sales exceeding one million copies. Peter Yarrow recalled that, when he told Dylan he would make more than $5,000 (equivalent to $40,000 in 2017[12]) from the publishing rights, Dylan was speechless.[13] Peter, Paul and Mary's version of the song also spent five weeks atop the easy listening chart.

The critic Andy Gill wrote,

"Blowin' in the Wind" marked a huge jump in Dylan's songwriting. Prior to this, efforts like "The Ballad of Donald White" and "The Death of Emmett Till" had been fairly simplistic bouts of reportage songwriting. "Blowin' in the Wind" was different: for the first time, Dylan discovered the effectiveness of moving from the particular to the general. Whereas "The Ballad of Donald White" would become completely redundant as soon as the eponymous criminal was executed, a song as vague as "Blowin' in the Wind" could be applied to just about any freedom issue. It remains the song with which Dylan's name is most inextricably linked, and safeguarded his reputation as a civil libertarian through any number of changes in style and attitude.[14]

Dylan performed the song for the first time on television in the UK in January 1963, when he appeared in the BBC television play Madhouse on Castle Street.[15] He also performed the song during his first national US television appearance, filmed in March 1963, a performance made available in 2005 on the DVD release of Martin Scorsese's PBS television documentary on Dylan, No Direction Home.

An allegation that the song was written by a high-school student named Lorre Wyatt and subsequently purchased or plagiarised by Dylan before he gained fame was reported in an article in Newsweek magazine in November 1963. The plagiarism claim was eventually shown to be untrue.[16][17]

The first line of the song ("How many roads must a man walk down?") is proposed as the "Ultimate Question" in the science fiction novel The Hitchhiker's Guide to the Galaxy, by Douglas Adams.

In the 1994 film Forrest Gump, Jenny sings this song for a show in a strip club and is introduced as "Bobbi Dylan". The film's soundtrack album features Joan Baez's 1976 live recording of the song, from her album From Every Stage.

In 1975, the song was included as poetry in a high-school English textbook in Sri Lanka. The textbook caused controversy because it replaced Shakespeare's work with Dylan's.[18][19]

During the protests against the Iraq War, commentators noted that protesters were resurrecting songs such as "Blowin' in the Wind" rather than creating new ones.[20]

The song has been embraced by many liberal churches, and in the 1960s and 1970s it was sung both in Catholic church "folk masses" and as a hymn in Protestant ones. In 1997, Bob Dylan performed three other songs at a Catholic church congress. Pope John Paul II, who was in attendance, told the crowd of some 300,000 young Italian Catholics that the answer was indeed "in the wind" â€“ not in the wind that blew things away, but rather "in the wind of the spirit" that would lead them to Christ. In 2007, Pope Benedict XVI (who had also been in attendance) wrote that he was uncomfortable with music stars such as Dylan performing in a church environment.[21]

In 2009, Dylan licensed the song to be used in an advertisement for the British consumer-owned Co-Operative Group. The Co-Op claimed that Dylan's decision was influenced by "the Co-Op's high ethical guidelines regarding fair trade and the environment." The Co-Op, which is owned by about 3 million consumers, also includes Britain's largest funeral parlour and farming business.[22][23]

He was described by David Barrett in 2017 as a 'living legend' and 'a true inspiration' to customer service representatives around the globe.[24]

"Blowin' in the Wind" has been recorded by hundreds of artists. The most commercially successful version is by folk music trio Peter, Paul and Mary, who released the song in June 1963, three weeks after The Freewheelin' Bob Dylan was issued. Albert Grossman, then managing both Dylan and Peter, Paul and Mary, brought the trio the song which they promptly recorded (on a single take) and released.[25] The trio's version, which was the title track of their third album, peaked at number 2 on the Billboard charts.[26] The group's version also went to number one on the Middle-Road charts for five weeks.[27]

“How many words can be written on a page, before they begin to bleed? How many books can one man own, before he has learned to read? How many meanings can he give to a phrase, before, from his lexicon he’s freed?”