Defect in germ cells, not in supporting cells, is the cause of male infertility in the jsd mutant mouse: proliferation of spermatogonial stem cells without differentiation

C57BL/6 (B6)-jsd/jsd male mice are sterile because of lack of spermatogenes is. To find the cause of the deficient spermatogenesis, we have examined wh ether the mutation phenotype is the result of a defect in germ cells or in supporting cells using germ cell transplantation. In the seminiferous tubul es of B6-jsd/jsd mutant mice, donor germ cells derived from the wild type G FP transgenic mouse (B6-+/+GFP) were able to undergo complete spermatogenes is, indicating that the juvenile spermatogonial depletion (jsd/jsd) mouse p ossesses normal supporting cell functions. In contrast, undifferentiated sp ermatogonia derived front B6-jsd/jsd mice were unable to differentiate in t he seminiferous tubules of W/W-v mice, even if the mutant germ cells succes sfully settled in the tubules. These results demonstrate that the deficienc y in spermatogenesis of B6-jsd/jsd mice can be ascribed to a defect in sper matogonia but not in their supporting cell environment. Furthermore, the de fect in B6-jsd/jsd spermatogonia is not in their ability to proliferate, bu t in their differentiation and may result from their hypersensitivity to hi gh concentrations of androgen in the testis.