Abstract
Summary
(1) FSH from beef pituitaries, powdered serum of the pregnant mare, and a commercial preparation of human pregnancy urine (Prolan, Elberfeld) were otherwise proved potent and then injected daily for 21 or 15 days into 65 rainbow trout (Salmo shasta?) aged 11 or 16 months. An additional group of 25 trout of the same brood served as control (NaCl injected), and all fish were maintained in their normal habitat at 51°F while under test. (2) A fraction of the males had sperm-producing testes before injection but an equal or greater number had unstimulated minute thread-like testes at the end of treatment. The largest oocytes in the ovaries of all groups were beginning to form yolk but no heavily yolked eggs were present. (3) Neither of the potent mammalian gonad-stimulating preparations used measurably stimulated either testes or ovaries in these trout. These results support the view that the FSH elaborated by pituitaries of fish differs qualitatively from that of mammals but much further study of the problem is needed.
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