In the ovarian follicle, it is the granulosa cells that are present throughout follicular development associated with the follicular basal lamina. The theca, on the other hand, only differentiates in bovine follicles at approximately the time of antrum formation, well after the basal lamina of the follicle has started increasing. Cultured granulosa cells have been shown to produce a basal lamina that structurally resembles the follicular basal lamina. birth control yasmin
By Northern blot analysis, granulosa cells were shown to express the a3 chain of type IV collagen and the 71 (old nomenclature: B2) chain of lam-inin. In a previous immunoelectron microscopy study, laminin was localized to CalliExder bodies, which are ultrastructurally similar to basal lamina and have been observed within the membrana granulosa of antral follicles in vivo (cow: unpublished results). Conversely, in some systems, mesenchymal production of basal lamina components have been shown, suggesting that cells of the theca might play a role in production of the follicular basal lamina.