A Quantitative Study of Ovulation in the Rabbit. ∗

Abstract

Evidence presented by Smith and Engle 1 points to the fact that there is a correlation between the amount of gonadal stimulating hormone of the anterior lobe of the hypophysis and the stages of the oestrous cycle. These investigators found that only a slight response was secured from glands taken from donors during the oestrous period, while a marked reaction was secured when glands were taken from animals which were in dioestrous.

We have tested the capacity of the anterior lobe of the hypophysis of the sow, taken at different periods of the oestrous cycle, to induce ovulation in the rabbit. Using the work of Corner 2 as a basis, it is possible to select sows at the different periods of the oestrous cycle. The head and the entire reproductive tract of these sows were brought to the laboratory from the killing floor within 30 minutes after the death of the animals. The hypophysis was removed and the anterior lobe dissected out and carefully weighed. It was ground up very thoroughly with sand in physiological saline, and centrifuged for 30 minutes. The supernatant fluid was drawn off and diluted to a point where 1 cc. of the fluid represented 5 mg. of anterior lobe tissue. These manipulations were carried out under sterile conditions. The follicles and corpora of the donor's ovaries were carefully measured and the ovaries were fixed in Bouin's fluid for histological study. Blocks from the uterus and the vagina were also fixed.

The saline suspension obtained from the anterior lobe tissue was injected intravenously in sexually mature female rabbits in various amounts. On the basis of 144 experiments, the following conclusions have been reached: