No abstract

No abstract

No abstract

No abstract

Summary. The pattern of cell division in the uterus of the guinea-pig has been studied, during the oestrous cycle (with and without mating) and after treatment of ovariectomized animals with ovarian hormones.During the oestrous cycle, there were many luminal epithelial cells undergoing mitosis just before and after the time of ovulation whilst mitosis counts in the glandular epithelium were maximal about 4 days after ovulation. In the stroma, cell division reached a peak on Day 6 of the cycle, just before the expected time of implantation.In ovariectomized animals, mitosis was stimulated by exogenous oestradiol, indicating that epithelial mitosis during the cycle is associated with follicular oestrogen secreted during pro-oestrus. Progesterone alone stimulated only a few mitoses in the stroma, but the number was increased considerably by the addition of a small quantity of oestradiol. This indicates that luteal progesterone cannot be solely responsible for the very high level of stromal mitosis on Days 5 and 6 of the cycle and suggests that some oestrogen is also being secreted at this time.