SUMMARY Pintail ducks captured from migrating flocks and held in captivity fail to show ovarian development. Bioassay of their pituitary glands revealed a lack of gonadotrophin secretion. In the closely related Mallards, which also fail to reproduce in captivity, avian gonadotrophin injections, either 15–30 mg/day alone or 10–12 mg/day in combination with diethylstilboestrol, caused nearly normal ovarian follicular development. Oestrogen and gonadotrophins acted synergistically to produce a series of follicles with normal gradations in size. Oestrogen alone stimulated ovarian weight of ducks and immature chickens, but in immature chickens it did not synergize with exogenous gonadotrophins.
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Phillips et al. (1960) studied this question.