Abnormal structure of the Y chromosome detected in bovine gonadal hypoplasia (XY female) by FISH.

The structure of the Y chromosome was investigated by FISH and G banding in 3 cases of bovine XY females shown by PCR to lack the SRY gene. Although 2 different repeat-DNA sequences (BC1.2 and btDYZ-1) hybridized to the short arm of the Y chromosome in a normal bull, they hybridized to both arms of the Y chromosome in the XY females. In the Y chromosome from XY females, only the centromeric region was darkly stained by G banding, in comparison with dark staining on the long arm of a normal Y chromosome. From the results obtained, it seemed that the Y chromosome from the XY females was structurally abnormal, namely an isochromosome with an identical short arm. Our results also confirm that SRY is located on the long arm of the Y chromosome in bovine.