ON TESTIS AND EPlDlDYMlS OF RATS - Pondicherry University ...

the most active in protein secretion in rats and boer (Brooks, 1981; Syntin cl ul.,
1996). High levels of several proteins that mediate antioxidant action are found in
epithelial cells and in epididymal fluid, which may protect epithelial and/ or sperm
cells against oxidative stress from exposure to endogenous reactive oxygen species or
exogenous toxic substances (Hinton er al., 1995; Jones, 1999). Expression of
secretory antioxidant factors has been shown to be region specific, indicating that the
need for antioxidant enzymes may vary along the epididymis. Some of the other
major proteins secreted by the epididymal epithelium possess carrier functions for thc
transport of retinol (Porter er ul., 1985) or of cholesterol (Baker el ul., 1993; KirchhofS
cr 01.. 1998).
Epididymis has been shown to be dependent on androgens secreted into the
peripheral circulation as well as other factors that are secreted directly into the
epididymal lumen from the seminiferous tubules. rete testis and efferent ducts (for
review. see Robaire er 01.. 2000). There is a time dependent dramatic weight loss of
the epididymis after androgen withdrawal and has been attributed to the loss of
spermatozoa and fluid from the lumen of the epididymis and in part due to changes in
the epithelium of the tissue (Klinefelter and Hess, 1998). Apoptotic cell death after
orchidectomy has been shown to appear first in the epithelium of the initial segment
ol' the rpididymis and subsequently in more distal segments (for review, src Robaire
rr ul.. 2000). The main androgen responsible for maintaining epididymal structure
and functions is the 5 a-reduced metabolites of testosterone. dihydrotestostcronc
(DHT). The rate-limiting enzyme in the pathway leading from testosterone to its 5 a-
reduced metabolites is 4-ene steroid 5 a-reductase (Hermo er a/., 1988). In the rat.
the levels of dihydrotestosterone have been shown to be approximately 10 fold higher
than those of testosterone in the caput and corpus epididymis, but the levels of these
androgens are similar in the cauda epididymis (Turner cr at.. 1984). l'estosteronc
entering the epididymis via the lumen is associated with transport of androgen binding
protein (ABP) from seminiferous tubule to the epididymis (Danzo, 1995). In rat.
epithelium in cauda epididymis is characterized by the presence of numerous clear
cells. These cells have been shown to be responsible for the phagocytosis of