Histologic study of endometriosis and examination of lymphatic drainage in and from the uterus.

Histologic study of endometriosis and investigation of lymphatic drainage in and out of the uterus were conducted to obtain more information on the histogenesis of endometriosis. Endometriosis is a disease originating from the normal endometrium, specifically from its basal layer. Internal endometriosis (adenomyosis) is caused mainly by direct invasion of the endometrium into the spaces located in the connective tissue of the muscle layer. Serous and ovarian types of endometriosis are frequently found together with adenomyosis. Endometrial fragments in vessels are detected in 4.5% of cases of endometriosis. Observation of serial sections proved that serous endometriosis is caused mainly by continuous or semicontinuous invasion of the tunica muscularis spaces primarily from adenomyosis lesions and partly from the endometrium. Confirmation of lymph flow into the ovary from the uterine body strongly suggests that ovarian endometriosis arises as a consequence of vascular (lymphatic) transport of endometrial fragments from adenomyosis lesions, serous endometriosis lesions, or the endometrium.