Freemartin - A Small Review

Freemartin is an infertile genetic female born with a normal fertile male with which it has exchanged blood and antigens characteristics that are unique to female and male. Freemartin or Martin Heifer is an unproductive female animal that the cattleman should identify it at birth and save feed and development costs. 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. If both fetuses are the same sex this is of no significance, but if they are different this condition will occur. When a heifer twin shares the uterus with a bull fetus, they also share the placental membranes connecting the fetuses with the dam. A joining of the placental membranes occurs at about the fortieth day of pregnancy, and thereafter, the fluids of the two fetuses are mixed. This causes exchange of blood and antigens carrying characteristics that are unique to each heifers and bulls. Male hormones pass from the male twin to the female twin and these affect each other in a way that causes each to develop with some characteristics of the other sex. Because of a transfer of hormones or a transfer of cells, the heifer's reproductive tract is severely underdeveloped and sometimes even contains some elements of a bull's reproductive tract. The ovaries of the freemartin do not develop correctly, and they remain very small. Also, the ovaries of a freemartin do not produce the hormones necessary to induce the behavioral signs of heat. Freemartinism cannot be prevented; however, it can be diagnosed in a number of ways ranging from simple examination of the placental membranes to chromosomal evaluation. Freemartins are occasionally used in stem cell and immunology research.