The heterosexual grafts of the embryonal gonads aging 16 days old were performed as the methods Macintyre (1956) used. Additionally the author grafted one or two embryonal ovaries of the same age in the subcapsular site and multiple embryonal testes of the same age in the similar site of the opposite kidney of the same host and allowed to develop at the sites for 3 weeks.

The explants removed from the host, were fixed in Bouin's fluid, embedded in paraffin, sectioned serially at 6 µ, and stained with hematoxylin and eosin.

The embryonal transplanted ovary with testis in close contact, was inhibited and depressed to the one side probably due to the more rapid growth and differentiation of the testis as compared with the ovary and contained a tubular structure (seminiferous-like tubule) in which the degenerating oocytes were found. The author presumed the testicular effect upon the mutual ovary as the activity of the diffused inductor substance derived from the testis.

In the group, which more than 15 embryonal testes (maximally 25 testes were grafted) were transplanted in the subcapsular site and one or two ovaries in the opposite site of the kidney of the same host, the ovarian grafts, which were at a distant site from the multiple testicular grafts, showed inhibited growth and differentiation by the similar appearance of the transplanted embryonal ovary with testis in mutual contact. By this observation the author considered the inhibited growth and differentiation of the effect of blood-borne inductor substance derived from the multiple testicular grafts of the opposite site of the host kidney.