Capacitation-related changes in antigen distribution on mouse sperm heads and its relation to fertilization rate in...

The anti-mouse sperm monoclonal antibody OBF13 did not react with fresh epididymal sperm. However, when sperm were incubated in a culture medium capable of inducing capacitation, the entire head of the sperm began to react with this antibody. This change of reactivity was not observed when sperm were incubated in a Ca2+-free medium. The change of the reactivity to the antibody was studied in relation to the fertilizing ability of sperm as measured in an in vitro fertilization system; a significant correlation was observed between the appearance of head-stained sperm and fertilization rate.