FOLLICULAR GROWTH AND OVULATION IN HYPOPHYSECTOMIZED HENS

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Abstract
Growth of ovarian follicles was induced in hypophysectomized laying hens by daily intramuscular injection of mammalian FSH, PMS or chicken anterior pituitary powder (CAP). The mammalian gonadotropins caused a pronounced increase in the number of follicles entering the initial phase of yellow yolk deposition, but did not support growth of follicles to mature size. The disproportional accumulation of small follicles resulted in the complete obliteration of the normal follicular hierarchy. CAP produced no ovcrstimulation of the smaller follicles and; in a significant number of birds, established a follicular order similar to that found in intact hens. In some CAP treated hens follicles developed to mature size by the end of the eight day experimental period. With a timed sequence of injection of ovulation-inducing substances up to five consecutive daily ovulations were obtained. The number of ovulations was limited by the ability of follicles to attain ovulable size and was independent of the type of gonadotropin used to stimulate follocular growth.