Spontaneous and follicular fluid-induced acrosome reaction in sperm samples from in vitro fertilizing and nonfertilizing normozoospermic patients

Purpose: One of the most challenging and intriguing groups of infertile patients is that of normozoospermic men who have repeatedly not achieved fertilization in vitro. These cases probably present a wide range of gamete disorders manifested at different stages of the fertilization process. The occurrence of spontaneous and follicular fluid (FF)-induced acrosome reactions (ARs) in in vitro fertilizing and nonfertilizing specimens from normozoospermic NF patients was assessed, and the effect of Percoll and cryopreservation on the incidence of ARs was evaluated. Methods: Semen samples from 62 normozoospermic (15 in vitro nonfertilizing and 47 fertilizing) patients were analyzed. Spermatozoa were double-stained with FITC-conjugated Pissum sativum lectin, to assess their acrosomal status, and propidium iodide, to evaluate their vitality, using flow cytometry analysis. Results: A lower aver age of AR incidence was observed in the nonfertilizing than in the fertilizing group with all treatments. Both groups exhibited an increase in the proportion of ARs following incubation with FF: This rise was most prominent when Percoll-separated fractions were used (15.8 and 25.6% AR in the nonfertilizing and fertilizing groups, respectively). Thawed cryopreserved and fresh fertilizing samples exhibited similar AR rates. Conclusions: That normozoospermic recurrently nonfertilizing compared to fertilizing semen samples have a lower capacity to undergo ARs is suggested.