Effect of peritoneal fluid, follicular fluid, and their volumetric mixture on acrosomal reactivity in vitro *

Objective To determine the effects of peritoneal and follicular fluids (PFs, FFs) on sperm acrosomal reaction (AR). Design Prospective, randomized study. Setting Three hospital-based infertility units. Patients Twenty-three women participating in GIFT programs; 23 men participating in AIH programs. Interventions Hormonal stimulation after buserelin desensitation; laparoscopy 36 hrs after hCG injection. Main outcome measure Percentage of acrosomally-reacted sperm. Results Compared with Earle's medium (control), moderate but significant increases of ARs were observed as function 1) of the relative content of FF in the incubation medium and 2) as function of time (these increases were constantly lower than those registered for the respective positive control, i.e. 2× frozen/thawed sperm). In contrast, when PF alone was present in the incubation medium, no such effects on AR were registered. Conclusions FF and mixtures of PF and FF—but not PF alone—seem to induce some rapid and time-dependent processes which finally lead to an AR. Therefore, and independently on the infertlility cause (tubal, male-dependent, unexplained infertlity), PF seems able to exert effects on sperm motility (Revelli et al., Fertil. Steril 57, 654–60 [1992]) while maintaining an unreacted sperm status.