Head

Abstract

The sperm head consists mainly of the nucleus and acrosome (Figs. 55, 56 and 57). Its shape, size and structure vary greatly in different species of mammals including marsupials (Guraya 1965, 1971a, Phillips 1975a, Harding et al. 1979, Sarafis et al. 1981, Holstein and Roosen-Runge 1981, Heath et al. 1983, Gledhill 1986). The spermatozoa of various primate species show, more or less, the same basic configuration of the head, except for some minor variations in its shape and size (Gould 1980). The greatest variation in morphology of primate spermatozoa has been shown to involve the size and shape of the acrosomal membrane and the number, size, and organization of the mitochondria in the sperm mid-piece (Bedford 1967, Pedersen 1970a, Zamboni et al. 1971, Guraya 1971a, Bernstein and Teichman 1972, Lung and Bahr 1972, Semczuk 1977, Holstein and Roosen-Runge 1981). The sperm nucleus can be seen to extend as far as the apex of the head (Figs. 56 and 57). Scanning electron microscope provides the most ideal method available at present for the study of sperm morphology, especially for reconstructuring an impression of a three-dimensional structure from two-dimensional images (Gould 1980, Breed 1983, 1984). In general, the head of the primate spermatozoon is somewhat flattened and paddle-shaped, with evidence of an increasing posterior thickness with increasing evolutionary development towards the great apes. The shape and size of the sperm head in chimpanzee and man are apparently very similar (Figs. 17 and 56).