Ovary: Immunolocalization of transforming growth factor-β1 and transforming growth factor-β2 in the mouse ovary during gonadotrophin-induced follicular maturation

An immunohistochemical approach was utilized to evaluate the cellular distribution of transforming growth factor-β 1 (TGFβ 1 ) and transforming growth factor β 2 (TGFβ 2 ) at different stages of follicle development in the prepubertal mouse ovary under the following conditions : (i) after pregnant mare's serum gonadotrophin (PMSG) treatment ; (ii) after PMSG and human chorionic gonadotrophin (HCG) treatment ; (iii) after PMSG and HCG treatment plus mating. In the immature ovary, TGFβ 1 and TGFβ 2 immunoreactivities are localized in theca and granulosa cells and in oocytes. After PMSG treatment, TGFβ 1 and TGFβ 2 immunoreactivities are localized in granulosa cells ; in addition, TGFβ 2 staining is noted in the matrix surrounding antral cells. Staining for both TGFβ 1 and TGFβ 2 drops in the theca but persists in the oocyte. PMSG plus HCG treatment results in a significant increase in TGFβ 1 and TGFβ 2 immunoreactivity in the theca and in the maintenance of TGFβ 1 staining in both basal granulosa cells and cumulus cells whereas TGFβ 2 immunoreactivity is essentially localized in the matrix surrounding cumulus cells. Staining for TGFβ 1 and TGFβ 2 persists in the oocyte. Following PMSG plus HCG treatment and mating, TGFβ 1 immunoreactivity is localized in the luteal cells of corpora lutea and TGFβ 2 shows a similar localization pattern. This study provides evidence that TGFβ 1 and TGFβ 2 peptides are expressed in specific cell types during induced follicular maturation in the mouse ovary.