THE REACTIVITY OF THE X-IRRADIATED OVARY OF THE RAT

Abstract

SUMMARY 1. The ovaries of adult rats were directly X-irradiated by means of a superficial irradiation apparatus, the rest of the body being screened with lead. A dose of 4400 r produced complete sterilization. None of the animals developed radiation sickness. 2. The sterilized ovary does not undergo compensatory hypertrophy after unilateral ovariectomy, nor does it increase in size in response to exogenous gonadotrophin. 3. After irradiation, short periods of vaginal cornification recur at increasingly irregular intervals; after a minimum of 5 days and usually within 40 days, the vaginal smear becomes continuously cornified. After the period of cornification, which lasts from 2 to 14 weeks, and during which the animals will not mate, the smears become similar to those seen in spayed animals. 4. In sterilized animals the uterus is smaller than normal, but as long as 26 weeks after treatment is still significantly larger than that of spayed controls. 5. These indications of oestrogenic effects continue after bilateral adrenalectomy. They cease after removal of the X-ray sterilized ovaries. 6. Changes in the weight of the body, thymus and spleen after X-irradiation are similar to, but less rapid than, those occurring after ovariectomy. The increase in the weight of the pituitary is greater than that after ovariectomy. The adrenal glands do not decrease in size, as they do after bilateral ovariectomy. 7. The pituitaries of X-ray sterilized animals contain more gonadotrophin than do those of control-operated litter-mates, and about the same amount as do those of spayed rats.