“…The degenerative changes observed after hypophysectomy in the corpora lutea of the rat (Smith, 1930), rabbit # (Smith & White, 1931), and ferret (Donovan, 1965) suggest that the pituitary gland produces some substance with a tropic action on the luteal cells. Results of experiments using different techniques show that LH possesses luteotropic action in the rat (Astwood, 1941, Von Berswordt, Wallrabe & Turner, 1961, ferret (Donovan, 1965), and mouse (Dresel, 1935): and probably in sheep (Denamuk, Martinet & Short, 1967. Domanski, Skrzeczkowski, Stupnicka Fitko & Dobrowolski, 1967.…”