Epididymal Cell Types and Their Functions

Abstract

The mammalian epididymis is a highly coiled duct that links the efferent ducts to the vas deferens. Overwhelming evidence points to the importance of this tissue in transforming spermatozoa leaving the testis as immotile cells, not having the ability to fertilize oocytes, into fully mature cells that have both the ability to swim and to recognize and fertilize eggs (Orgebin-Crist et al., 1975; Turner, 1995; Jones, 1999). Although under pathological conditions, it would appear that spermatozoa can undertake these functions very high up in the excurrent duct system (Silber, 1989; see Schoysman, this volume), under normal conditions, the acquisition of these functions is essentially completed in most species only by the time sperm enter the proximal cauda epididymidis (Robaire and Hermo, 1988; Cooper, 1986; Hermo et al. 1994a; Turner, 1995). In addition to sperm maturation, the epididymis also plays an important role in sperm transport, concentration, protection, and storage (Setchell et al., 1993; Hinton and Palladino, 1995; Cornwall and Hann, 1995; Robaire and Viger, 1995; Turner, 1995; Orgebin-Crist et al., 1996; Jones, 1999; Kirchhoff, 1999; Cooper and Yeung, 1999).