Morphological Study of the Cyclic Changes in the Endocervical Epithelium

In order to examine the cyclic changes in the endocervical epithelium, fresh human endocervical specimens were obtained from 60 cases for observation by light microscopy (LM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The results obtained were as follows: 1) The endocervical epithelium was composed of ciliated cells and secretory cells at a ratio of 1:5-10 which did not vary by menstrual cycle, pregnancy and age. 2) Cyclic changes of ciliated cells were not observed in the menstrual cycle, but decrease in number and tip-thinning of the cilia were found in the postmenopausal phase by SEM observation. 3) Dilatation and complexity of the glandular lumen and increase in cell size reached a peak in the ovulatory phase. The findings of secretory cells in the first trimester of pregnancy were the same as those of the ovulatory phase and atrophic changes and simplified formation of the gland were observed in the postmenopausal phase. 4) SEM observation showed surface projections of various sizes and slightly dilated, round and shortened microvilli on the secretory cells in the ovulatory phase and the first trimester of pregnancy. During the postmenopausal phase, atrophic changes such as flattening of the cell surface and decrease and shortening of microvilli were observed. 5) TEM observation showed a peak in secretory granules and organelles in both number and size and exocytotic secretion during the ovulatory phase and the findings observed during the first trimester of pregnancy were similar to those during the ovulatory phase.