Ultrastructural changes in endometriotic implants during the menstrual cycle.

This report, the first ultrastructural study of endometriotic implants, compares the ectopic endometrium in 14 patients with that found in the uterus. The ultrastructural features of most of the glands of the ectopic endometrium resemble those of the corresponding glands lining the uterus. Specific ultrastructural characteristics associated with ovulation, such as giant mitochondria and nuclear channel systems, however, could not be detected in ectopic tissue. Although no pathognomonic electron microscopic characteristics were found in the ectopic endometrium, it was generally possible to assign each sample to a particular phase of the menstrual cycle.