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

and steroidogenic processes as Leydig and precursor cells have been shown to contain
receptors for androgen (Verhoeven, 1980). Testosterone secretion in the prepubertal
rats reduced following treatment with an androgen receptor antagonist (Puwis and
Hansson, 1978). Androgen receptor mRNA and protein levels are reported to be
lower in adult rather than immature Leydig cells, which might result from down
regulation exerted by the pubertal rise in androgen production (Shan and Hardy,
1992). Prolactin has been shown to increase the number of LH receptors and could
potentiate steroidogenic effect of LH on Leydig cells and testicular prolactin receptors
have been shown to be confined to the interstitial tissue of the testis (Johnson and
Everitt, 1995). Prolactin also increases the uptake of androgen and increases
Sa-reductase activity (Johnson and Everitt, 1995).
1.1.1.5 Paracrine regulation of testicular functions
Leydig cells, Sertoli cells, germ cells and peritubular myoid cells have been
shown to interact with each other in order to maintain testicular functions.
Cryptocrine communications are reported between germ cells and Sertoli cells in the
seminiferous tubules (Funder, 1990). It has been reported that stimulatory effect of
Sertoli cells on germ cells mediated by diffusible factors and to obtain full expression
of these stimulation germ cells must be in contact with Sertoli cells (Rivarola er ul.,
1985). Seminiferous tubules have been shown to secrete a meiosis inducing
substance and its secretion is maximal at stage VIIc-d of the spermatogenic cycle, just
before the onset of premeiotic DNA synthesis in preleptotene spermatocytes
(Parvinen, 1982). Regulation of Sertoli cell function by germ cells has been shown in
in vivo and in virro studies (Saez ef al., 1991). Regulation of FSH and testosterone on
spermatogenesis is reported to be mediated by Sertoli cells, which contain FSH and
androgen receptors (Tindall er al., 1977). Sertoli cells synthesize and secrete
transport proteins, growth factors that are regulated by FSH and also modulate by
local mechanisms related to the spermatogenic cycles. The nutrient and growth
factors required for spermatogenesis was shown to be transported from the