A cytochemical study on surface charges and lectin-binding sites in epididymal and ejaculated spermatozoa of Macaca...

Changes in electronegative and electropositive surface charges and in lectin receptors (concanavalin A and wheat germ agglutinin) were investigated on sperm plasma membranes of the monkey (Macaca fascicularis) during epididymal transit and after ejaculation. Electronegative charges at pH 1.8, which were uniformly distributed on the whole plasma membrane of caput epididymal spermatozoa, increased mainly on the postacrosomal cap and the tail during epididymal passage. Electropositive charges at pH 9 were simultaneously found on the whole cell surface of caput epididymal spermatozoa with a stronger labeling on the acrosomal apex, the postacrosomal cap, and the tail. These charges disappeared during passage through the epididymis corpus. The surface distribution of lectin receptors varied inversely during epididymal transit with an increase in concanavalin A receptors and a decrease in wheat germ agglutinin receptors. These data show that changes in the monkey sperm plasma membrane during epididymal maturation occur in the distal corpus of the epididymis.