Several significant concepts have emerged from the impressive mass of information on the basic principles of GH function.
Before 1955 no distinctive differences in growth hormone effect on various animals had been noted. Now it has been demonstrated that growth hormone derived from certain animals fails to show definite results and, in some instances, has no activity in specimens from other species. In general, growth hormone obtained from the more advanced species will be active in the same or in genetically lower groups; the reverse fails to occur (47) and, in particular, GH preparations from other animals have been found inactive in man.
Fish or bovine GH, for example, are both effective in the fish (fundulus, trout), whether intact or hypophysectomized, while beef GH was slightly more active than fish hormone (244, 590, 590 A, 591, 592). Fish GH has been found inactive in the rat. The immature female rat