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

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.