Clinical, cytogenetic and molecular studies on sterile stallion and mare affected by XXY and sex reversal syndromes, respectively

Abstract: Clinical, cytogenetic and molecular observations on a sterile stallion 2n=65, XXY and a sterile mare 2n=64, XY are reported. The XXY stallion was a pure case since all cells showed the same chromosome constitution. In the cells of mare XY, no SRY gene was found by both FISH- and molecular analyses. Both carriers show normal body conformation but were sterile because the stallion had no spermatozoa in the ejaculate, as revealed by microscope observation, and the mare showed the typical gonadal dysgenesis since both the uterus and ovaries were hypoplasic, as revealed by both rectal palpation and ultrasonic analysis. Although a mutation and/or deletion of SRY gene seems to be involved in the sex reversal, this syndrome is not yet fully understood. The possibility of other genes playing an important role in this syndrome and changes in the protein encoded by SRY are discussed.