Immunolocalization of anti-Mullerian hormone in bovine testes and ovaries during fetal development

The anti-Mullerian hormone (AMH) or Mullerian Inhibiting Substance (MIS), produced by the Sertoli cells induces the regression of Mullerian ducts in male embryos. Granulosa cells from ovarian follicle are homologous to Sertoli cells and produce AMH. The aim of this study was the immunolocalization of AMH in the testicles and ovaries of bovine fetuses at different ages. Gonads from bovine fetuses between 4 and 7 months (24-98 CRL) were collected in a local slaughterhouse, fixed in 10% formaldehyde, and processed for conventional histology and embedded in paraffin cut with a rotative microtome, deparaffinized, and subjected to immunohistochemistry using the anti- AMH 1:50 (SC 28912, Santa Cruz Biotechnology) according to the manufacturer's instructions. Immunostaining was observed in the cytoplasm of Sertoli cells, within the sexual cords (developing seminiferous tubules) at all ages and was not observed in gonocytes and interstitial tissue. In the ovary there was light staining in granulosa cells but not in the theca cells, however, intense staining was observed in the cytoplasm of the oocyte of primordial, primary, secondary and antral follicles, at all ages analyzed, suggesting that despite being produced by granulosa cells, AMH concentrates in the oocyte cytoplasm. The importance of AMH in sexual differentiation and action in Muller's ducts is well understood, however there are no studies on the role of this protein in gonadal development, this being the first report of AMH immunolocalization in fetal bovine testis and ovaries, requiring further studies on the action and importance of AMH in the gonadal development of bovine fetuses.