Japanese Journal of Veterinary Research;Volume 13, Number 2

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CHROMOSOME STUDIES ON HETEROSEXUAL TWINS IN CATTLE : II SIGNIFICANCE OF SEX-CHROMOSOME CHIMERISM (XX/XY) IN EARLY DIAGNOSIS OF FREEMARTIN

KANAGAWA, Hiroshi;KAWATA, Keiichiro;ISHIKAWA, Tsune

Permalink : http://hdl.handle.net/2115/1807
JaLCDOI : 10.14943/jjvr.13.2.43

Abstract

Chromosome analysis was carried out on 6 pairs of heterosexual twin cattle and also 5 normal cows from non-freemartin heterosexual twins. Culture of leukocytes from blood and colchicine treatment of bone marrow cells were used. The results may be summarzied as follows : 1) Sex-chromosome chimerism (XX/XY) was detected in all cases of 6 pairs of the freemartin and its male co-twin. The statistical analyses between XX/XY ratios in freemartins and their co-twins, and also the ratios in leukocytes and bone marrow cells showed no significant differences (P<0.05). 2) In all cases of 5 normal cows from the non-freemartin heterosexual twins as controls, no sex-chromosome chimerism was observed. Thus, it is hoped to be able to use chromosome analysis with leukocyte culture as an accurate early diagnostic method for freemartins. 3) It seems reasonable to think that the male calf co-twined with a freemartin may be cytologically distinguished from single born or homosexual twin males, because the former was of sex-chromosome chimerism. 4) Basic mechanisms of bovine freemartinism were discussed from the viewpoint of chromosomal cytology.

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