SUPPRESSIVE EFFECT OF FETAL TESTES ON DEVELOPMENT OF FETAL OVARIES TRANSPLANTED INTO ADULT MALES IN THE RAT

The age-related testicular effect on the ovarian primordia was studied by combined transplantation of fetal testes and ovaries in adult male hosts. First, ovarian primordia of 14-day fetal rats were transplante d into a renal subcapsular position of castrated or intact adult male rats. In both the castrated and the intact hosts, most of the ovarian transplants developed normally with only 3 of them having in part semi niferous tubule-like structures in addition to normal ovarian structur e. Second, a 14-day ovary was combined with a fetal testis the age of which varied from 13- to 18-day, and the combination was transplanted. In the combination of a 14-day ovary and a 13-day testis, the results varied in such a way that the ovary or the testis alone developed or otherwise, both gonads developed well. In union with 15- to 18-day tes tes, the ovaries did not develop, although the testes developed well. These results suggest that the 14-day ovarian primordia have a slight reactiveness to androgens of host rats and that the 13-day fetal teste s begin to inhibit the development of 14-day ovaries co-transplanted w ith them.