Structure of the right testis of sexually mature genetically female fowl experimentally masculinized during embryonic life and submitted to a posthatching left castration.

Posthatching left castration of genetically female fowl, Gallus domesticus, preceded, during embryonic life, by a masculinizing treatment associating a testis graft and an antiestrogen resulted in the development of the right rudimentary gonad into a testis. Examined after the sexual maturity, the right testis of most treated animals was entirely composed of seminiferous tubules possessing a spermatogenic cell complement. Spermiogenesis proceeded to the stage of spermatozoon in 4 out of 17 treated animals and was almost as well organized as in a normal cock testis in 3 of them. Testis development appeared then as clearly improved, compared to that described previously in only left-castrated, with or without treatment with an antiestrogen, or only sex-reversed female fowl. The possible mechanism of this improvement is discussed.