Oestradiol‐17β is a local factor inducing the early stage of spermatogenesis in mouse testes

Summary This study was undertaken to elucidate the effect of testicular oestradiol‐17β (E2) on spermatogenesis. Spermatogonial development and spermatogenic gene expression in testicular germ cells were investigated using an in vitro culture system supplemented with E2. E2 stimulated spermatocytogenic development of cultured testicular germ cells regardless of the addition of follicle‐stimulating hormone and testosterone to the culture medium. E2 also induced the expression of genes encoding synaptonemal complex protein 1 and protamine 1, proteins required for spermatogenesis. In conclusion, the results of this study suggest that E2 is a spermatocytogenic factor that acts via the stimulation of spermatogenic gene expression.