THE IMMUNOHISTOCHEMICAL LOCALIZATION OF TRANSFORMING GROWTH-FACTOR-BETA-2 IN THE FETAL AND NEONATAL RAT TESTIS

The localization of transforming growth factor beta-2 (TGF beta 2) in the fetal and neonatal testis (from day 13.5 of fetal life to postnata l day 9) was investigated by an immunohistochemical staining method em ploying a specific polyclonal antibody. Immunostaining appeared on fet al day 13.5 in primitive Sertoli cells as they begin to come in contac t with each other and surround the germ cells to form the seminiferous cords. Staining in Sertoli cells was still clearly observed until fet al day 16.5 and became faint or undetectable from fetal day 18.5 onwar ds. In fetal-type Leydig cells, a positive reaction for TGF beta 2 app eared on day 16.5 and became very intense from day 18.5 onwards. In th e germ cells, immunoreactivity for TGF beta 2 appeared on fetal day 20 .5, rose to a maximum on postnatal day 4 and decreased thereafter. On postnatal day 9, staining was still present in type A spermatogonia an d absent in type B spermatogonia. No immunoreactivity was detected in peritubular cells on any day studied. In conclusion, our results are i n favour of an autocrine/paracrine role of TGF beta 2 in the different iation of the testis during the perinatal period. It may be involved i n the organization of the seminiferous cords, the regulation of testos terone production and the regulation of the number of perm cells. When compared with the immunolocalization of TGF beta 1 that we have previ ously reported [1], the present study suggests that the roles of TGF b eta 2 in the developing rat testis can be specific but also overlap fr om those of TGF beta 1. (C) 1997 Elsevier Science Ireland Ltd.