Percentages of acrosome-reacted sperm in human semen close to liquefaction and following acrosome-reaction inducing treatment.

OBJECTIVES: To compare spermatozoa from normal and subnormal seminal specimens in their ability to undergo the acrosome reaction, as defined by the triple-staining method. METHODS: Normal (39) and abnormal (23) specimens were examined by staining promptly after liquefaction. In a total of 32 specimens, the reaction was examined before and after acrosome-reaction-inducing treatment, which was essentially incubation of isolated sperm in BWW containing 0.3% BSA and 4 mM calcium chloride. RESULTS: Percentage of vital acrosome-reacted sperm (true acrosome reaction) of untreated specimens: normal, 10.0 +/- 4.9%, abnormal, 5.3 +/- 3.6% (P < .001). After treatment: increase in reacted sperm from normal specimens, 9.0 +/- 7.1% to 22.7 +/- 14.0% (P = .005); abnormal specimens, 5.4 +/- 2.9% to 7.3 +/- 4.2% (NS). CONCLUSIONS: Low capability of sperm to undergo the acrosome reaction might be a decisive factor in the low fertility potential characterizing the majority of abnormal semen. Effort in infertility treatment should be directed to increasing the proportion of acrosome-reacted sperm.