Effects of anti-sperm antibodies on human sperm ultrastructure and function

The ultrastructural appearance of a highly motile population of spermatozoa from a fertile donor was evaluated following antibody labeling with each of several sperm head-directed anti-sperm antibodies (ASAs) and subsequent incubation in a capacitating medium in vitro. Acrosomes were classified into categories which are believed to represent stages in the acrosome reaction. Quantitative analysis revealed no difference in acrosomal morphology of antibody-labeled sperm between treatment groups despite a varying degree of enhancement or inhibition of sperm egg-penetrating ability. We conclude that ASAs affect gamete interaction through mechanisms other than an alteration in the acrosome reaction.