Sperm Motility

Abstract

The mammalian spermatozoa show motility which is brought about by their tail. The latter consists of various specialized components, as already discussed in detail in Chap. X. Sperm motility forms one of the most important parameters in assessing the fertility potential of a semen specimen, as immotile human sperm cannot penetrate cervical mucus (Amelar et al. 1980). The type of movement also influences fertilizing capacity as the vigorous beating of the sperm tail is necessary for penetration of the sperm head through the corona radiata to fertilize the ovum (Nelson 1985). Under physiological conditions, motility and fertilizing ability of spermatozoa are usually closely related to each other, but there are situations when these two functions of spermatozoa get dissociated (Mann 1975), suggesting that sperm movement alone is not a sufficient criterion for fertilizing capacity. Mature mammalian spermatozoa present within the distal regions of the male reproductive tract show little or no movement in situ, but can become highly motile following their release into suitable salt solutions (Mann 1964, Turner and Howards 1978, Amelar et al. 1980, Mohri and Yanagimachi 1980, Nelson et al. 1980a, b, Mann and Lutwak-Mann 1981). The ultrastructural molecular and functional organization of each component of the tail have been discussed in Chap. X. The axoneme is composed of two principal proteins, the dynein ATPase enzymes and the microtubule protein tubulin, and as many as 100 minor component proteins.