Epididymal epithelium: Its contribution to the formation of a luminal fluid microenvironment

Abstract

To understand the process of sperm maturation, an understanding of interactions between the spermatozoa with the luminal fluid microenvironment and with the epididymal epithelium is necessary. The composition of epididymal luminal fluid of several species is well documented but the manner by which the epididymis contributes to the formation of this specialized milieu is not so well understood. A major role played by the epididymis is to finely regulate the movement of molecules into and out of the lumen. This ensures that as spermatozoa progress along the duct they are exposed to a continually changing, but optimal environment necessary for their maturation and survival. This review focusses on our current understanding of the contributions of the epididymal epithelium to the formation of a specialized luminal fluid microenvironment. The role of the blood-epididymis barrier, the composition of the epididymal luminal fluid, the permeability properties of the epididymal epithelium, and recent studies on a number of luminal fluid proteins and expression of the genes which encode these proteins are discussed.

Changes in lectin-binding sites on epididymal cells during postnatal development of the mouse

“…The epididymal epithelium is known to secrete a variety of proteins and provides a luminal microenvironment for sperm maturation and storage under the control of androgen (Hinton and Palladino, 1995). The epididymal ducts of mice can be divided into 5 regions -I, II, III, IV, and V -according to the morphological properties of the epithelial cells in each region (Takano, 1980).…”

Regulation of luminal acidification in the male reproductive tract via cell–cell crosstalk

“…Spermatozoa produced by the testis are immature, and they cannot find and fertilize an egg. They acquire their motility and fertilizing capacity during their passage through the lumen of the epididymis, which is composed of one single convoluted tubule (Hinton and Palladino, 1995;Jones and Murdoch, 1996;Orgebin-Crist, 2003;Robaire and Viger, 1995;Yeung et al, 1993). Epithelial cells lining the epididymal duct play a vital role in establishing the optimal environment for the maturation and storage of spermatozoa (Da Silva et al, 2007b;Hinton and Palladino, 1995;Pastor-Soler et al, 2005;Robaire and Viger, 1995;Wong et al, 2002).…”

A novel role for SED1 (MFG-E8) in maintaining the integrity of the epididymal epithelium

“…Interspersed among the principal cells are clear cells, a specialized epithelial cell type distinct from principal cells in both protein expression and function (Robaire and Hinton, 2002;Setchell et al, 1994). Clear cells are present throughout the caput, corpus and cauda, and express VATPase proton transporters that contribute to the reduction in luminal pH from 7.3 to 6.8, which maintains sperm in a quiescent state during storage (Breton et al, 1996;Hinton and Palladino, 1995;Levine and Marsh, 1971).…”