Expression of Sox9 in granulosa cells lacking the estrogen receptors, ERα and ERβ

Ovaries from adult mice lacking both estrogen receptors ERα and ERβ (ERαβKO mice) contain abnormal cells sharing morphologic features with Sertoli cells, which are located mainly in the interstitial compartment. We show here that these cells express the Sertoli cell markers TIF1β, TIF2, and Sox9. In ERαβKO ovaries, Sox9 is expressed by granulosa cells before the morphologic appearance of Sertoli cells, but neither by granulosa cell precursors nor by non-Sertolian interstitial cells. These findings suggest that functional Sertoli cells can transdifferentiate from mature granulosa cells devoid of estrogen receptors as a result of Sox9 expression. © 2002 Wiley-Liss, Inc.