CHEMICAL-COMPOSITION AND PROTEIN-SOURCE IN THE CAPACITATION MEDIUM SIGNIFICANTLY AFFECT THE ABILITY OF HUMAN SPERMATOZOA TO UNDERGO FOLLICULAR-FLUID INDUCED ACROSOME REACTION

We studied the effect of media composition on sperm capacitation, usin g Biggers - Whitten - Whittingham (BWW) medium, Ham's-F10 and a modifi ed Tyrode's medium (HSM) supplemented with bovine serum albumin (BSA) or fetal cord serum (FCS). We evaluated the effect of chemical environ ment and protein supplementation on the sperm motion parameters of cur vilinear velocity and linearity, and on the ability of incubated sperm atozoa to undergo follicular fluid induced acrosome reaction. Neither chemical composition nor protein supplementation of capacitation media greatly affected motion parameters after 2 h incubation. Furthermore, chemical composition had only a small effect on the ability of sperma tozoa to undergo the acrosome reaction upon exposure to follicular flu id. A higher proportion of spermatozoa underwent acrosome reaction aft er incubation in HSM (8% control (C); 28% follicular fluid) than in BW W (8% C, 17% follicular fluid) or Ham's F-10 (6% C, 19% follicular flu id). By contrast, protein source proved critical in determining acroso me reaction inducibility. Spermatozoa incubated in BSA-supplemented me dia showed a 4-fold increase in acrosomal discharge when exposed to fo llicular fluid (6% C, 22% follicular fluid) compared to controls while spermatozoa incubated in FCS were unable to undergo acrosome reaction (6% C, 6% follicular fluid). Simultaneous addition of FCS to BSA capa citation medium blocked acrosome reaction inducibility and the late ad dition of BSA, after sperm incubation in FCS, did not facilitate acros ome reaction. We propose that an inhibitor of sperm capacitation is pr esent in FCS and therefore, the selection of optimum incubation condit ions for spermatozoa may be of critical importance when evaluating or treating infertile patients.