Mechanism of action of IUDs: an ultrastructural view.

Endometrial samples from 64 women using different types of IUDs were used to study the ultrastructural changes of the human endometrium as influenced by nonmedicated and copper devices, using SEM and TEM in an attempt to explain the physiological mechanism of their actions. The absence of cytoplasmic macro-apocrine secretory granules with copper devices and their defective separation with nonmedicated IUDs support the theory that the IUD interferes with the carbohydrate metabolism and secretory function of the endometrial cells. It also indicates that IUDs may function through the interference with the blastocyst-endometrial interaction and blastocyst survival.

Ultrastructural changes in human endometrium with copper and nonmedicated IUDs in utero.

Scanning and transmission electron microscopy were used for a study of the surface and glandular ultrastructure of human endometrium in the presence of different types of IUDs at comparable phases of the menstrual cycle. The aim of the study was to compare the effect of the nonmedicated with the copper and multiload copper devices to further explain the differences in their contraceptive potencies and their mechanism of action. The endometrium was evaluated at and away from the IUD; emphasis was put on the ultrastructure of endometrial gland openings, secretory activity, cellular glycogen content, ciliated cells, microvillous pattern, and kinocilia.