Development of Embryonic Mouse Gonads Transferred to the Spleen: Effects of Transplantation Combined with Genotypic Autonomy

Certain aspects of the pleiotropic relationship between the embryonic anaemia and germ-cell defect produced by deleterious alleles of the W-series in the mouse were tested by transfer of gonads from new-borns and 12–16-day embryos into a neutral site with rich blood-supply, the spleen of adult castrates. Splenic residence cut down the recovery of ovarian tissue from transplants at early stages, and slightly inhibited the amount of spermatogenesis at all stages. In spite of such environmental limitations, it was clear that at all stages transplants of both ovaries and testes contained fewer germ-cells at the 14-day post-natal stage if the donor were of defective sterile genotype than if it were of normal fertile type. This supports the hypothesis that genotypic autonomy of germ-cell level is established by the 12th day of embryonic life, and further development is independent of the W-genotype of surrounding tissue. The implications of these findings for understanding of pleiotropic relations are discussed.