In the endocervix there are single ciliated epithelial cells or patches of ciliated cells, independent of the phase of the cycle. In the isthmus a great many ciliated cells are present. In the endometrium, few cil ated cells are present, within the glandular and surface epithelium. These cells are more frequent in the midcycle. The growth of ciliated cells seems to be stimulated by estrogen and depressed by progesterone. Ciliated cells are not found in the atrophic endometrium. The ciliary apparatus is formed from basal bodies within the cell. The living ciliated epithelium shows a fast planar regular beat of a frequency of about 150 strokes/min. The only known function of the ciliary beat seems to be that of keeping the gland-secreted fluid barely in motion.