Developmental studies of sperm surface antigens using sperm-specific monoclonal antibodies

Sperm-specific monoclonal antibodies generated against mouse sperm isoantigens were used to analyze the developmental expressions of sperm surface antigens during different stages of spermatogenesis. Indirect immunofluorescent assays using the freshly isolated testicular cells from mature and immature mice revealed that a number of monoclonal antibodies did not stain the surface of spermatogenic cells in testis. Instead these antibodies reacted with the sperm surface antigens in testis and/or epididymis. Further analysis was performed using frozen testicular sections from mice of day 14 to day 30 after birth. It was generally observed that a significant number of these antibodies reacted with the cytoplasmic components of spermatogenic cells in testis at the postmeiotic stages (e.g. day 22 after birth). After meiosis, the percentage of seminiferous tubules that were stained by immunofluorescence was found to increase with the ages of the mice. The results of this study suggest that some cytoplasmic components (especially acrosomal) of spermatogenic cells are expressed postmeiotically in testis, but later translocated to the sperm surface during very late stages of spermatogenesis.