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

extratubular environment or synthesized by the Sertoli cells and delivered to the
developing germinal cells within the tubule (Skinner, 1987).
Germ cells require lactate for swival but they are unable to metabolize
glucose (Jutte el al., 1982), this energy substrate can be supplied by Sertoli cells
which are able to transform glucose to lactate, a process stimulated by FSH (June er
al., 1983) and insulin-like growth factor I (IGF-I) (Mita and Hall, 1982). Lactate and
pyruvate secretions by Sertoli cells have been reported to regulate and maintain
spermatogenesis (Grootegoed and de Boer, 1989). Degeneration of germ cells has
been reported due to the absence of proper substrate required for their metabolic
activiries (June el al.. 1981). It has been reported that human Sertoli cells cultured
with FSH and testosterone have been reported to produce lactate, estradiol and
transfemn (Foucault el a[., 1992).
Sertoli cells have been shown to synthesize and secrete transport proteins and
growth factors (Bardin el d.. 1988; Ritzen el al.. 1989). which are regulated by FSH.
Several Sertoli cell secretory products have now been identified which include
transferrin, androgen binding protein, ceruioplasmin, plasminogen activator, clusterin
(sulfate glycoprotein-2). a2 macroglobulin, testin sulfated glycoprotein-I, testiburnin
and others (for review, see Mruk and Cheng, 2000a). The stimulatory effects of
Sertoli cells on germ cells have been reported which are mediated either by cell-cell
contacts (Russell, 1980) and! or by diffusible factors (Rivarola er a!.. 1985). Sertoli
cells have been reported to secrete several growth factors including IGF-I (Cailleau el
01.. 1990), TF-a (Skinner et al.. 1989). TGF-P (Skinner and Moses, 1989). FGF
(Smith el al., 1989) and seminiferous growth factor (Bellve and Zheng, 1989). Germ
cells have been shown to regulate biosynthesis of rat Sertoli cell clusterin. a:-
macroglobulin and testin (Grima et al., 1992). Peritubular cells have been shown to
enhance the production of a Leydig cell stimulatory factor when co-cultured with
Senoli cells (Verhoeven and Cailleau. 1986). Peritubular cells have been reportcd 10
secrete a factor PMod-S, which stimulated secretion of Sertoli cell proteins (Skinner
el al., 1988). PMod-S production was reported to be under androgen regulation