ALPHA(6) SUBUNIT OF INTEGRINS IN THE DEVELOPMENT AND SEX-DIFFERENTIATION OF THE MOUSE OVARY

The localization of the alpha(6) subunit of integrins in the ovary was studied by conventional and immunolabeling light and electron microsc opy starting from the pregonadal embryonic phase until adulthood. The formation of gonadal blastema cells included an initial expression of the alpha(6) subunit on the plasma membranes of all blastema cells. Su bsequently the reaction for the alpha(6) subunit became restricted in groups of these cells, which differentiated into gonadal cord cells, t he precursors of follicular cells. The alpha(6) subunit was also found in the cells of the mesonephric duct, mesonephric tubules, and the ov arian rete. Reorganization of the gonadal cords into follicles at birt h was accompanied with strong and uniform re-expression of the alpha(6 ) subunit on the surface of the cord cells, Vascular endothelial cells and the cells of the postnatal surface epithelium remained positive f or the alpha(6) integrin subunit. In larger follicles, the intensity o f the reaction for the integrin subunit varied. The theca cells of gro wing follicles contained the alpha(6) subunit, The results show that t his subunit of integrins is present in phases of increased adhesion an d aggregation, and that its expression probably is involved in the reg ulation of ovarian epithelial differentiation. The distribution of alp ha(6) integrin in ovarian cells shows potentially important sex-specif ic and developmental differences in epithelial organization when compa red with respective changes found earlier by us in the male gonad. (C) 1995 Wiley-Liss, Inc.