Highly purified gonadotropin preparations from chicken, turkey, and ostrich were tested in in vivo and in vitro experiments with domestic cockerels, turkeys, ducks, and Japanese quail to evaluate the hypothesis that acute testicular androgen secretion in birds is highly specific for LH, as suggested by previous studies with only Japanese quail. The results of these experiments uniformly supported
... [Show full abstract] this hypothesis. Results of heterologous tests were qualitatively the same as results of homologous incubations of immature turkey testes with turkey gonadotropins and of cockerel testes with chicken gonadotropins. The same high degree of LH specificity of androgen secretion was as apparent with sheep gonadotropins as with avian gonadotropins, and as apparent in tests with sexually immature cockerels, turkeys, and ducks as in tests with sexually mature quail. In vitro results were qualitatively the same whether testes were incubated whole or after being quartered, mechanically dissociated, or dissociated with collagenase. In addition to being essentially inactive in acutely stimulating testicular androgen secretion by itself, FSH was also inactive in increasing acute responses when given concomitantly with LH in an in vivo experiment with 4-day-old cockerels and ovine gonadotropins and in an in vitro incubation of immature turkey testes with turkey gonadotropins. Thus, with regard to gonadotropin specificity of acute testicular androgen secretion, birds seem to have diverged from reptiles in the same way as mammals.