ABSTRACT

The seminiferous epithelium in sexually mature and active testis is made up of germ cells at varying levels of development, and Sertoli cells, which are the only somatic, non-dividing cells of the epithelium. Sertoli cells have been described in some detail in Chapter 2. Sertoli cells have multiple functions, including, but not limited to, contributing significantly to the formation of the blood-testis barrier by means of the so-called Sertoli-Sertoli junctional complexes (Dym and Fawcett 1970; Fawcett et al. 1970; Dym 1973), providing anchorage and nutrition for, as well as regulation of, germ cells during development (Morris et al. 1987; Jégou 1991; Skinner et al. 1991; Vogl et al. 1991). The germ cells usually develop, and grow older as they move from the basement membrane of the seminiferous epithelium toward the tubular lumen. Thus, the most primitive or immature germ cells lie on the basement membrane and the mature germ cells, the spermatozoa, line the lumen of the seminiferous tubule. Germ cells develop in close association with one another because as they divide they maintain close linkage through intercellular bridges which are the result of incomplete cytoplasmic divisions (Fawcett 1961).