Investigation of lymphatic vessels in Eutopic human endometrium with frozen sections: Significance of lymphatic vessels in menstruation

Information on lymphatic vessels in human endometrium is unsettled. We planned to study immunocytochemical presence of the elusive lymphatic vessels in the eutopic human endometrium with frozen sections. By immunostaining lymphatic vessels from eutopic human endometrium, we studied lymphatic vessels and blood vessels in the post-menstrual, proliferative, secretary and menstrual stages. We used D2–40 and LYVE-1 as lymphatic vessels markers as compared to von Willebrand factor as a blood vessel marker. There was consistent presence of lymphatic vessels in myometrium and basalis. Blood vessels supply the repairing functionals while lymphatic vessels grew longitudinally from basalis to deep functionalis during proliferative phase and further grew from lower to the middle to upper secretary functionalis in late secretary phase. Thus, lymphatic vessels grew from the basalis after menstruation and grew to entire functionalis in the late secretary phase. In the late secretary menstrual phase, D2–40 immunostained larger but less lymphatic vessels in deep functionalis while LYVE-1 immunostained smaller but more lymphatic vessels in the entire functionalis. We concluded that ample blood vessels supplied the entire repair endometrium while lymphatic vessels did not catch up with the fast-growing blood vessels in the functionalis. D2–40 immunostains less but larger lymphatic vessels while LYVE-1 immunostains small but more lymphatic vessels. The less lymphatic vessels in the late secretary phase may contribute to interstitial endometrial edema during menstrual shedding. The presence of lymphatic vessels in the endometrium during the menstrual period implies the presence of sliver of lymphatic fluid in the menstrual fluid.