Restricted domains of the sperm surface.

The plasma membrane of the sperm is a mosaic, with different moieties restricted to specific areas of the head or tail. Some of these heterogeneously distributed surface components are inserted into the membrane during spermatogenesis while others are acquired during post-testicular maturation, as the sperm passes through the epididymis. A variety of surface probes have been used to examine sperm, with lectins and antibodies proving to be effective at relating quantitative and qualitative changes to specific areas of the sperm surface. More recently, monoclonal antibodies have been used in conjunction with surface labeling procedures to study the distribution, time and site of origin and possible roles of sperm components. The use of such highly specific probes in conjunction with high resolution SEM instruments and new molecular labeling techniques offer considerable promise in addressing these problems.