Freemartins are known to have been described by the Roman writer Varro, who called them "taura".EARLY RECOGNITION OF THE FREEMARTIN CONDITION IN HEIFERS TWINBORN WITH BULLS, by W.W. Swett, C.A. Matthews, and R. R. Graves, in the Journal of Agricultural Research, vol. 61, no. 8 (October 15, 1940) The 18th-century physician John Hunter discovered that a freemartin always has a male twin.
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A freemartin is the normal outcome of mixed twins in all cattle species which have been studied. It does not normally occur in most other mammals, though it has been recorded in sheep, goats, and pigs.
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The etymology of the term "freemartin" is uncertain: speculations include that "free" may indicate "willing" (referring to the freemartin's willingness to work) or "exempt from reproduction" (referring to its sterility, or to a farmer's decision to not bother trying to breed a freemartin, or both), or that it may be derived from a Flemish word for a cow which gives no milk and/or has ceased to be capable of bearing offspring; "martin" is generally held to derive from an Irish or Gaelic word for "cow" or "heifer", although connections to Martinmas have also been posited.
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Thus, by analyzing these tissues, one can investigate the capacity of hematopoietic stem cells or other circulating cells to produce other tissues in addition to blood. The freemartin model allows one to analyze perfectly healthy and unmanipulated animals, without resorting to transplantation often used in stem cell research.
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2005: pg 145) Several researchers made the discovery that a freemartin results when a female fetus has its chorion fuse in the uterus with that of a male twin. The result was published in 1916 by Tandler and Keller.Keller, K. and Tandler, J.: Wiener Tieraztl. Wochensch., 3, 513-526 (1916).
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A sub-breed, Freemartins, are female dragons who were born sterile, and can presumably be of any breed, although the only identified Freemartins (Nesessitas and Alsebra) are both Greens. A third Freemartin named Zed Dek is mentioned, but not identified. Freemartins are generally faster and smarter than other types. Their sterility makes them unable to "fertilize the eggs" as the dragons express it.
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Freemartins are occasionally used in stem cell and immunology research. During fetal development cells are exchanged between the fused circulations of the bovine twins. Up to 95% of the freemartin's blood cells can be derived from those of her twin brother. Male-derived cells and their progeny can be easily visualized in the freemartin tissues, as only they contain the male Y chromosome.
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Twins are common in many mammal species, including cats, sheep, ferrets, giant pandas, dolphins, dogs, deer, marmosets, tamarins, and elephants. The incidence of twinning among cattle is about 1–4%, and research is underway to improve the odds of twinning, which can be more profitable for the breeder if complications can be sidestepped or managed. A female calf that is the twin of a bull becomes partially masculinized and is known as a freemartin.
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Microchimerism occurs in most pairs of twins in cattle. In cattle (and other bovines), the placentae of fraternal twins usually fuse and the twins share blood circulation, resulting in exchange of cell lines. If the twins are a male–female pair, then XX/XY microchimerism results, and male hormones partially masculinize the heifer (female), creating a martin heifer or freemartin. Freemartins appear female, but are infertile and so cannot be used for breeding or dairy production.
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A plate showing a "Free Martin" from the collected works of John Hunter. A freemartin or free-martin (sometimes martin heifer) is an infertile female mammal with masculinized behavior and non-functioning ovaries. Genetically the animal is chimeric: Karyotyping of a sample of cells shows XX/XY chromosomes. The animal originates as a female (XX), but acquires the male (XY) component in utero by exchange of some cellular material from a male twin, via vascular connections between placentas: an example of microchimerism.
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The phenomenon of the freemartin, a female bovine that is behaviorally masculine and lacks functioning ovaries, is commonly associated with cattle, but does occur to some extent in sheep. The instance of freemartins in sheep may be increasing in concert with the rise in twinning (freemartins are the result of male-female twin combinations). The Flehmen response is exhibited by rams when they smell the urine of a ewe in oestrous. The vomeronasal organ has receptors which detect the oestrogens in the ewe's urine.
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In most cattle twins, the blood vessels in the chorions become interconnected, creating a shared circulation for both twins. If both fetuses are the same sex this is of no significance, but if they are different, male hormones pass from the male twin to the female twin. The male hormones (testosterone and anti-Müllerian hormone) then masculinize the female twin, and the result is a freemartin. The degree of masculinization is greater if the fusion occurs earlier in the pregnancy - in about ten percent of cases no fusion takes place and the female remains fertile.
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From the late 1940s until 1991, world affairs were dominated by the Cold War, in which the U.S. and its allies faced the Soviet Union and its allies. There was no large-scale fighting but instead numerous regional wars as well as the ever-present threat of a catastrophic nuclear war.Ralph B. Levering, The cold war, 1945–1987 (1988) online freeMartin McCauley, Russia, America, and the Cold War, 1949–1991 (1998), A British perspective; online free In 1948 the United States enacted the Marshall Plan, which supplied Western Europe—including Germany—with US$13 billion in reconstruction aid. Stalin vetoed any participation by East European nations.
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If suspected, a test can be done to detect the presence of the male Y-chromosomes in some circulating white blood cells of the subject. Genetic testing for the Y-chromosome can be performed within days of birth and can aid in the early identification of a sterile female bovine. Physical examination of the calf may also reveal differences: a subjective assessment is that frequently there is a tuft of hair at the ventral tip of the vulva in a freemartin heifer atypical in fertile heifer calves. Also, often many (but not all) freemartins will have a shortened length of vagina compared with that of a fertile heifer.
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" They also stated that light "constant pressure on the clitoris produced an initial burst of single unit firing (maximum frequencies 170–255 Hz) followed by rapid adaptation and a sustained firing (maximum 40 Hz), which was maintained during the stimulation" and that further examination of tonic firing "indicate that the clitoris is innervated by mechano-sensitive myelinated afferent fibers in the pudental nerve which project centrally to the region of the dorsal commissure in the L7-S1 spinal cord". The external phenotype and reproductive behavior of 21 freemartin sheep and two male pseudohermaphrodite sheep were recorded with the aim of identifying any characteristics that could predict a failure to breed. The vagina's length and the size and shape of the vulva and clitoris were among the aspects analyzed. While the study reported that "a number of physical and behavioural abnormalities were detected," it also concluded that "the only consistent finding in all 23 animals was a short vagina which varied in length from 3.1 to 7.0 cm, compared with 10 to 14 cm in normal animals.
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