Reacting mouse sperm with monoclonal H-Y antibodies does not influence sex ratio of eggs fertilized in vitro

The fertility of Y-bearing mouse sperm was examined after reacting cauda epididymal sperm with monoclonal H-Y antibodies and protein A sensitized sheep red blood cells. Treated sperm were used for the in vitro fertilization of mouse oocytes which subsequently produced live offspring. There was no significant shift in the sex ratio in favor of females, suggesting that X- and Y-bearing sperm may share the surface antigen. Additional studies were directed toward ascertaining whether haploid expression, as measured by the presence of H-Y antigen, occurs in epididymal sperm or during their capacitation in vitro. Ligation of the corpus epididymus, preventing subsequent transport of sperm to the cauda region, resulted in a linear decrease in H-Y positive cauda sperm. By 17 days after ligation, no positively reacting sperm were observed. Incubation of cauda epididymal sperm for 3 h in capacitating medium eliminated positive reaction by the capacitated sperm to the H-Y antiserum. Furthermore, the percentage of H-Y-positive sperm from different regions of the male reproductive tract appeared to decrease during their transport from the testis to the epididymus and vas deferens. We suggest that H-Y antigen appears on the sperm surface during association with testicular constituents and is removed during epididymal transport and capacitation. No evidence of haploid expression by epididymal mouse sperm was found.