In-vitro differentiation of type A spermatogonia in mouse cryptorchid testis.

Cryptorchid testes from adult mice were incubated in calf serum-supplemented medium. There was an effective differentiation of adult type A spermatogonia up to the pachytene stage of meiotid division whcih resembled the process of spermatogenesis in vivo. In the absence of calf serum, type A spermatogonia did not differentiate at all. They differentiated when the serum was present for the first day, but was absent for the rest of cultivation. These results indicate that serum is necessary for only the early process of spermatogenesis from type A spermatogonia in vitro and not for the further processes of germ cell differentiation. Type A spermatogonia cultured in serum-free medium retained the ability to differentiate for at least 3 days.