IMMUNOHISTOCHEMICAL LOCALIZATIONS OF TGF-BETA IN THE DEVELOPING RAT GONADS

Beta types of transforming growth factor (TGF-betas) are known to have a variety of types of endocrine, paracrine and autocrine roles in the adult and embryonic tissues. In order to clarify the participation of TGF-beta in rat gonadal differentiation, immunohistochemical expression of TGF-beta was chronologically studied in perinatal rat gonads. Sprague-Dawley rat gonads from gestational day (GD) 13 to postnatal day (PD) 21 were fixed in Methacarn solution and stained with a polyclonal antibody against native porcine platelet TGF-beta in the rabbit by using avidin-biotin complex technique. Immunohistochemical reactivity to TGF-beta was positive in the germ cells of both sexes from GD 13 to PD 21. Moderate and marked staining was seen in male germ cells from GD 16 to PD 21 and in female germ cells from GD 21 to PD 11. Leydig/interstitial cells in male gonads were stained from GD 15, and moderate and marked staining from GD 16 to PD 11. On the other hand, the Sertoli or peritubular cells was not stained during the perinatal period. In contrast to the male gonads, the granulosa and interstitial cells in female gonads were stained on PDs 11 and 21. The Wolffian ducts in males and the Mullerian ducts in females expressed positive but weak reactivity during the perinatal period. The mesonephric tubules were faintly stained from GD 13 to 18. These results indicate that TGF-beta shows discrete cell-specific patterns of expression at various stages of the rat gonadal development and may participate in the rat gonadal development and differentiation.