[Surface ultrastructural cyclic change of the human uterine glandular and lining epithelia. A scanning electron...

The purpose of this study is to take advantage of scanning electron microscopy on the topographic alterations of the human uterine glandular epithelium which occur during the various stages of the menstrual cycle. 1) Both glandular and lining epithelia were mainly covered with nonciliated cells which reflected the cyclical changes during the menstrual cycle. In the early proliferative phase, microvilli were short and the apical cellular membrane slightly protruded, however microvilli and the apical cellular membrane gradually developed toward the end of proliferative phase. Compared with the surface epithelium, the glandular epithelium showed a monotonous change because of the uniform surface structure. 2) Numerous ciliogenesis can be observed on the lining epithelium in the late proliferative phase. In contrast, ciliogenesis could not be recognized in the glandular epithelium. 3) In the glandular epithelium, an apocrine type of secretion was recognized for several days after ovulation and they were seen to cluster occasionally. It was suggested that the secretion activity differed among various parts of the endometrial gland. 4) The menopausal phase was divided into two groups: the early stage of the postmenopausal phase resembled the early proliferative phase and had a fusiform and flattened cells with slender microvilli. Ciliated cells were seen in clusters. On the other hand, the advanced postmenopausal phase had uniform flattened cells with sparse microvilli and ciliated cells were extremely rare. 5) The lining epithelium of a female fetus was recognized with a slight protrusion of the apical cellular membrane with long microvilli.