Seminal Antigens: Their Alteration in the Genital Tract of Female Rabbits and During Partial In Vitro Capacitation with Beta Amylase and Beta Glucuronidase1
By use of immunofluorescence with antisera to sperm-specific and sperm-coating antigens, it was observed that rabbit sperm residing in the uterus for 10 h lost sperm-coating antigens. This loss resulted in the unmasking of sperm-specific acrosomal antigenic sites. Sperm recovered from the fallopian tubes of estrual rabbits showed more (P < 0.01) of this alteration than sperm from the uterus. The environment in an estral uterus was more efficient in removing sperm-coating antigens, especially from the region of the postnuclear cap, than that in a pseudopregnant uterus. In vitro incubation of rabbit sperm in a solution containing 0.1 mg or 1 mg β-glucuronidase per 100 ml for 6 h or 1 mg β-amylase per 100 ml for 8 h, partially mimicked the effect of an estral uterus on removal of sperm-coating antigens and on sperm capacitation. Partial in vitro capacitation was achieved by use of either β-amylase or β-glucuronidase. It was concluded that steps leading to full capacitation could be initiated in the buffer alone; they were speeded up with the in vitro enzyme treatments, and were finally completed in the female.