Asymmetry of spermiation and sperm surface charge patterns over the giant acrosome in the musk shrew Suncus murinus.

Abstract

Spermatozoa of the shrew S. murinus, a mammal with abdominal testes, exhibit 4 unusual features: a giant acrosome, a dorsoventral asymmetry of their spermiation, a dorsoventral asymmetry of their head surface character, and apparent surface maturity upon entering the epididymis. A Sertoli cell-periacrosomal cisternal complex envelops the giant acrosome during spermatid maturation. Spermiation is heralded by asymmetrical disorganization of the subplasmalemmal components of this complex and is completed by retraction of the Sertoli cell from the ventral and then the dorsal face of the spermatid head. This sequence of release is correlated with an asynchronous acquisition of negative surface charges on the spermatid head.sbd.demonstrable on glutaraldehyde-stabilized cells by the binding at pH 1.8 of positively charged colloidal particles of ferric oxide. Mature epididymal spermatozoa exhibit an asymmetry in the patterns of distribution of bound colloid over the dorsal vs. ventral surfaces of the sperm head, as well as regional differences between the tail midpiece and principal piece. Surface distributions of anionic residues and lectin [Con A (concanavalin A)]-binding sites characteristic of mature Suncus spermatozoa are demonstrable within the testis, unlike the situation in most mammals where distinct modifications of the sperm surface occur during epididymal passage.