MODIFICATIONS IN THE PLASMA-MEMBRANES OF EPIDIDYMAL RAM SPERMATOZOA DURING MATURATION AND INCUBATION INUTERO

Ram spermatozoa from corpus and cauda epididymis have been examined for the surface distribution of concanavalin A binding sites and electropositive and electronegative charges before and after incubation in utero under conditions able to induce capacitation. The electronegative charges at pH 1.8 which are uniformly distributed on the heads of corpus or cauda epididymal spermatozoa increase on the flagella of cauda epididymal spermatozoa. These charges are reduced to a great extent after incubation in utero. Electropositive charges at pH 9 are abundant on the postacrosomal area of both corpus and cauda epididymis spermatozoa. In addition, they appear on the apical ridge of cauda epididymis spermatozoa and do not change markedly after in utero incubation of cauda epididymal sperm. In contrast, the membrane of Corpus epididymal spermatozoa become heavily electropositive after in utero incubation, possibly due to acrosome leakages. Concanavalin A binding, which is important on corpus and cauda epididymal spermatozoa, greatly decreases in most cells from cauda epididymis after in utero incubation. The possible relations with the appearance of fertilizing ability are evoked. © 1979 Academic Press, Inc.