Abstract
SUMMARY: The direct influence of oestriol and progesterone, and a combination of these hormones, on endometrium of guinea-pigs has been studied in organ culture. Progesterone stimulated the size and number of stromal cells, and provoked slight dilation of uterine glands. The glands were more numerous and widely dilated in the presence of oestriol, and the number and size of stromal cells were even greater than with progesterone alone. A combination of the two hormones led to the simultaneous appearance of synergism—well-preserved epithelium and glands of a secretory nature, and antagonism—there being fewer stromal cells of a smaller size than with either hormone alone. The significance of these results is discussed in relation to the effects of the hormones in vivo. The inhibitory action of progesterone on the appearance of the cystic hyperplasia of the uterine glands provoked by oestriol was noted.