GM 17. Freemartin early detection by means of cariologic analysis

Freemartins are XX/XY chimeras that develop as a consequence of fusion of the chorioallantoic circulation in pregnancy of heterosexual cotwins. The external appearance of a freemartin may vary from an apparently normal female to a somewhat masculinized individual. With the purpose to know the degree of chimerism and its relationship with the masculination and developmental aberration of reproductive organs, which varies from animal to animal, chromosomal analysis was performed in peripheral blood cells of three females born cotwins with a male, one of them was 2 years old and the other two were 4 months old. The oldest was sacrified, because had been demonstrated that it was sterile. The macro and microanatomy were performed to know the degree of masculinization of the female organs.It was recognized ovotestes, uterus, seminal vesicle, deferent duct, vagina, clitoris and vulva. The three females exhibited XX/XY chimerism in the lymphocytes analyzed. 30, 45 and 60 % of XY lymphocytes were observed in the female 2 years old and in both 4 months old respectively.These results demonstrated that is convenient to perform early the chromosomal diagnosis in all the heifers born heterosexual cotwins. This conclusion is supported since the females 4 month old apparently normal were sterile, which was confirmed when they were 2 years old. Usually the farmer waits until the cow demonstrated to be sterile to decide her sacrifice. The premature diagnosis of the chimerism XX/XY is a good orientation about the future cow reproductive efficiency