SOME EXPERIMENTS ON THE EFFECTS OF HYPOPHYSECTOMY AND PITUITARY IMPLANTATIONS ON THE MALE FUNDULUS HETEROCLITUS

¹ From the Mt. Desert Island Marine Biological Laboratory, Salsbury Cove, Maine, and Trinity College. Hartford, Connecticut

Adult male Fundulus, hypophysectomized shortly after maximal testicular development, show an inhibition of spermatogenesis for stages beyond those of spermatogonial multiplication. Spermatogonial divisions do not become numerous. The inhibition of the later stages is not immediately affected, since a few cysts continue to form sperm for as long as one month after hypophysectomy. These results confirm those of Matthews.

Both hypophysectomized adult male Fundulus and fish which received blank operations were maintained until sexual regression was well established. Implantations of twenty or fifteen pituitaries from normal male Fundulus caused within two weeks a recrudescence of the testes. Non-implanted controls showed none of this activity. It is concluded that the pituitary of the adult male Fundulus contains gonadotropic material and that the testes of adult Fundulus, hypophysectomized or not, are responsive to this material.

The normal relation of the pituitary to the annual sexual cycle is discussed.