Testosterone in the Fetal Rat Testis1

Origin, proliferation and differentiation of Leydig cells

“…This hypothesis is based on evidence that Leydig cells express several neural specific proteins such as neural cell adhesion molecule, neurofilament protein 200, and microtubular-associated protein (Mayerhofer et al 1992a, Davidoff et al 1993, Middendorff et al 1993. In the rat morphological (Jost et al 1981) and functional differentiation, the ability to produce testosterone (Warren et al 1973;Habert & Picon 1984) of Leydig cells is first observable on day 15·5 dpc (Fig. 2).…”

Development of Negative Feedback Control of the Hypothalamo-Pituitary-Gonadal Axis in the Male Rat Fetus

“…On day 18 of gestation, when during normal develop ment testicular activity is already maximally stimulated [25,26], no difference between the testicular testosterone content of fetuses immunized against testosterone and control fetuses was detectable. However, at day 19, when the testicular activity of normal fetuses decreases, the testosterone content of the testes of immunized fetuses was significantly higher compared to the controls.…”

“…Thereafter, the testosterone levels de cline towards term [18,19,21,25,26], Inves tigations in anencephalics [28] and in labora tory animals [5,7,9,11,12,17,22] provide evidence that during the time of sexual differ entiation testicular function comes under fe tal pituitary control. Our own previous find ings in neonates bom to testosterone-immu nized mothers [2] as well as recent reports of other investigators [15,20,23] suggest the existence of a reciprocal relationship between the hypothalamopituitary system and the testes at least in late gestation.…”

Adenylate cyclase in foetal rat testes and its stimulation by LH and NaF

“…Rat testes have been demonstrated to synthesize testosterone during foetal life [1,2]. Testosterone secretion could be observed in vitro and enhanced with dibutyryl cyclic adenosine-3'-5'-monophosphate (dibutyryl cyclic AMP) [3] and with LH [4].…”