The researchers validated their results by injecting the lab-grown spermatogonia stem cells into mouse testes. There, the cells underwent normal spermatogenesis, producing functional spermatids.

Mouse spermatogonia stem cells can be made, but inefficiently, which is why Dr. Yukiko Ishikura, another contributor to the study, concluded that optimizing the differentiation process was needed.

It is the process in which diploid spermatogonia undergo meiosis to produce haploid spermatids. Each spermatogonium undergoes mitotic division, resultanting into new cells called primary ...