Immunohistochemical detection of the expression of the α subunit of inhibin, TGF‐β, basic‐FGF and IGF‐II in fetal ovarian grafts grown with fetal testes beneath the kidney capsule of adult castrated male rats

In order to characterize the participation of growth factors in gonadal differentiation and development, we examined patterns of expression of the α subunit of inhibin, transforming growth factor-β (TGF-β), basic fibroblast growth factor (basic FGF) and insulin-like growth factor-II (IGF-II) immunohistochemically in experimentally induced ovotestes. Ovotestes were derived from ovaries of fetal rats on gestational day (GD) 13 that had been co-grafted with fetal testes (GD 17) beneath the kidney capsule of adult castrated males and examined on the 7th, 14th and 21st days after transplantation (TD). Reactivity with antibodies against the α subunit of inhibin and basic FGF was observed in the Sertoli cells in both ovotestes and testes on TD 14 and on TD7, 14 and 21, respectively. Expression of IGF-II was also recognized in the Leydig/interstitial cells in both types of graft on TD 14 and 21. Therefore, the gonadal somatic cells in the testicular region of the ovotestes had immunohistochemical properties similar to those in the co-grafted testes. However, the somatic cells in the ovarian region of the ovotestes had immunohistochemical profiles different from those in solitary grafted ovaries. The germ cells in the ovotestes showed some differences in patterns of expression when compared with those in co-grafted testes and solitary grafted ovaries: expression of basic FGF was recognized in the germ cells in ovotestes on TD 21 but not in co-grafted testes; expression of IGF-II was recognized in the germ cells in ovotestes on TD 21 but not in solitary grafted ovaries. These results indicate that the immunohistochemical properties that reflect expression of growth factors in female gonadal somatic cells were changed to properties that resemble those of male gonads by the co-grafted fetal testes. © 1995 Wiley-Liss, Inc.