Plasma Membrane and its Surface Components

Abstract

Spermatozoa, like other cells, have a continuous limiting membrane or plasma membrane, the nature and properties of which are of special interest as the molecular character of its surface is an important determinant of the spermatozoon’s ability to recognize and fuse with the egg (Shapiro 1984, Monroy and Rosati 1983, Peterson et al. 1985, O’Rand et al. 1984) and is the primary determinant of species specificity in fertilization. Therefore, during the past decade, the plasma membrane of spermatozoa as well as their surface components have been extensively studied with modern techniques of cytochemistry, biochemistry, lectins, freeze-fracturing, high resolution electron microscopy, and other physical techniques (Young and Goodman 1980, Holt 1980, 1984, Olson and Gould 1981, Holt and North 1985). These studies have provided basic information about the fine structure and chemical and physical properties of the plasma membrane of spermatozoa and about the regional distribution and density of general classes of compounds or specific activities on cell surfaces. In spite of these advances, our knowledge of membrane organization in spermatozoa is limited. Actually, the spermatozoon plasma membrane is characterized by specific regional specializations of the surface properties (or mosaicism) (Friend 1982, Courtens et al. 1982, Mack and Everingham 1983, Holt 1984).