Cell organization in the stroma of the rat uterus. II. Responses to progesterone in the ovariectomised rat.

The organisation and activity of cells in the uterine stroma of ovariectomised rats have been studied over the 24 hours following an injection of progesterone. Autoradiographically, the rate of incorporation of [3H]lysine falls 1 hour after progesterone, rising progressively at 3 and 7 hours to levels higher than in control animals. A gradient of grain density is evident at 1, 3 and 7 hours, higher in regions adjacent to luminal epithelium than near the muscularis. No such gradient appears relative to glandular epithelium. Morphometric studies show that the array of stromal cells 24 hours after progesterone is similar to that in control rats, except that cells near the luminal epithelium are larger in the former group. At intermediate times, changes in cell size and spacing occur throughout the stroma in patterns that vary with distance from luminal epithelium. The organisation and activity of cells in the uterine stroma change in response to progesterone in a manner conditioned by their position in the uterus, in particular by their distance from luminal epithelium.