Differentiation of germ cells in seminiferous tubules transplanted to testes of germ cell‐deficient mice of W/W v and SI/SI d genotypes

(WB × C57BL/6)F 1 ‐ W/W (hereafter, WCB6F 1 ‐ SI/SI d ) mice are sterile due to the deficient spermatogenesis in the testes. The cause of deficient spermatogenesis in WBB6F 1 ‐ W/W mice is considered to be a defect in germ cells themselves, whereas that in WCB6F 1 ‐ SI/SI d mice is considered to be a defect in tissue environment necessary for differentiation of germ cells. Seminiferous tubules isolated from cryptorchid testes of C57BL/6‐+/+ mice were transplanted into the testes of WBB6F 1 ‐ W/W and WCB6F 1 ‐ SI/SI d mice to clarify that the extratubular environment of these mice was intact or not. Type A spermatogonia in the transplanted tubules normally differentiated into spermatids, suggesting that the extratubular environment is intact in both WBB6F 1 ‐ W/W and WCB6F 1 ‐ SI/SI d mice.