EFFECT OF FOLLICULAR-FLUID ON THE KINETICS OF HUMAN SPERM ACROSOME REACTION IN-VITRO

The purpose of the present study was to evaluate the kinetics of human sperm acrosome reaction in vitro using the triple stain technique. Ac rosome reaction was studied in sperm samples from 16 fertile men 2, 6, and 9 h after ejaculation, following incubation in culture medium (CM ; Ham's F-10), with a mixture of CM and follicular fluid (FF), or with FF only. Incubation of sperm samples without the influence of any med ium served as control. The highest proportion of living acrosome-react ed sperm after a 2-h incubation period occurred in samples incubated w ith FF (18%), followed by samples incubated with the mixture (15.2%), and then with CM (11.8%). The proportion of living sperm that had unde rgone the acrosome reaction in the control group was significantly low er (5.7%, p < 0.05). After 6 h of incubation, live acrosome-reacted sp erm in FF had increased to 39%, in the mixture to 35.5%, and in CM to 30.5%, whereas in the control group the increase was only 6.3% (p < 0. 05). After 9 h of incubation, the percentage of living reacted sperm s howed a decline compared with the percentage at 6 h. This decline was greater in samples incubated with FF (from 39 to 19.8%) than in sample s incubated with the mixture (from 35.5 to 23.6%). Samples incubated i n CM only showed a small decrease from 30.5 to 28.4%, while in the con trol group this percentage decreased from 6.3 to 2.3%. In conclusion, incubation of sperm in suitable media favorably influences the acrosom e reaction, inducing an increase in the percentage of live acrosome-re acted sperm. The most beneficial effect on the induction of acrosome r eaction is exercised by FF, followed by the mixture, and then the CM a fter 6 h of incubation. The study of the acrosome reaction in vitro co uld be helpful in assessing more accurately the fertilizing potential of human sperm.