Spermatids from mice after cryptorchid and reversal operations can initiate normal embryo development.

We investigated fertilization and embryo development following intracytoplasmic injection of round spermatids collected from mice after cryptorchid and reversal operations. The rates of oocyte activation, blastocyst formation, and development to live offspring were compared after intracytoplasmic injection of round spermatids from intact, cryptorchid males (control) or males that had undergone the reversal operation. The incidence of normal fertilization and embryo development was about the same when the oocytes were injected with spermatids from intact cryptorchid males or males after reversal operation. The rates of the development of two-cell embryos to term were also about the same, regardless of the origin of spermatids injected. Round spermatids from both cryptorchid and previously cryptorchid testes can initiate normal embryo development when injected into mature oocytes.