H. Merchantlarios et N. Morenomendoza, MESONEPHRIC STROMAL CELLS DIFFERENTIATE INTO LEYDIG-CELLS IN THE MOUSE FETAL TESTIS, Experimental cell research, 244(1), 1998, pp. 230-238
Circumstantial evidence has suggested that Sry expression probably occ
urs in pre-Sertoli cells, implying that they produce signals required
for testis differentiation. From experiments involving gonad/mesonephr
os grafts it has been shown that, at 11.5 days postcoitum stromal cell
s from the mesonephros invade the male gonad. Although in the grafted
testes, Leydig cells appeared among the stromal cells, in these studie
s their origin remained elusive. In the current study, we reconstructe
d urogenital ridges in organ culture by grafting morphologically undif
ferentiated male genital ridges from CD-1 embryos, to mesonephroi from
ROSA26 transgenic embryos whose cells express the bacterial beta-gala
ctosidase. With an improved technique for the detection of beta-gal en
zyme activity in electronmicrographs, we studied cell migration and di
fferentiation of mesonephric cells into the testis in reconstructed ur
ogenital ridges with XY or XX mesonephroi. It was found that, in addit
ion to differentiation of myoid and connective cells, some migratory m
esonephric cells acquired ultrastructural features of steroidogenic Le
ydig cells. Several beta-gal positive cells differentiated as Leydig c
ells in go. nads grafted with either male or female mesonephros. The r
esults suggest that mesonephric cells responded to putative signal(s)
produced in the male gonad and participate in morphogenesis and cell d
ifferentiation of the fetal testis. (C) 1998 Academic Press.