Cyclic Changes of Nerve Fibers in Human Endometrium

Objective: The presence of nerve fibers in human endometrium remains unsettled but recent immunocytochemical studies have shown that there was increased innervation in the endometrium from women with endometriosis and some nerve fibers in the normally cycling human endometrium. In the current study, we used uterine tissue cryosections from normal cycling women, which previously provided better immunocytochemical staining for lymphatic vessels than in paraffin sections. Materials and Methods: A total of 16 cases from normally cycling women were included representing menstrual, early proliferative, early to late secretary phase. Neurofilament and CD 56 were used as immunocytochemical markers for nerve fibers with cryosections. Results: There were consistent presence of nerve fibers in myometrium and basalis. Few small nerve fibers were identified in early proliferative endometrium and more nerve fibers were present in lower-half functionalis from mid-secretary phase. Late-secretary functionalis showed less nerve fibers in the upper-half than the lower-half functionalis, implying growing nerve fibers from lower functionalis to upper functionalis in late-secretary phase. Conclusion: Nerve fibers appeared to cyclically grow from basalis to lower functionalis and then from lower functionalis to upper functionalis concomitantly with blood vessels in normally cycling human endometrium. These cycling endometrial nerve fibers consisted mostly of nonmyelinated small nerve fibers, which may transmit pelvic pain in the normally cycling women.

Cyclic Changes of Lymphatic Vessels in Human Endometrium

Objective: The presence of lymphatic vessels in endometrium has been controversial and recent immunocytochemical studies with routinely paraffin embedded sections revealed lymphatic vessels in basalis and occasionally in functionalis. We aimed to investigate endometrial lymphatic vessels by immunocytochemical staining using cryosections, which provided better and consistent immunostaining for lymphatic vessels with a lymphatic marker, D2-40. We aimed further to explore the structure-function relationship of lymphatic vessels in the menstrual cycle. Materials and Methods: Sixteen cases of endometrium from menstrual, early-proliferative to latesecretary phase were immunostained for D2-40 and lymphatic vessels were morphometrically analyzed for functionalis, basalis and myometrium, respectively. Results: Lymphatic vessels were consistently most numerous in myometrium, followed by basalis in all phases whereas menstrual endometrium showed small, fragmented aggregates of lymphatic vessels in thin basalis. Earlyto mid-secretary endometrium revealed many lymphatic vessels in basalis and lower-functionalis with few lymphatic vessels in upper-functionalis. Late-secretary endometrium revealed more lymphatic vessels in upper-functionalis with dilated walls, which then burst at the surface of functionalis. Conclusions: These degenerating lymphatic vessels with markedly dilated lumen in upper-functionalis may contribute to lymphatic leakage in late-secretary phase. These immunostained lymphatic vessels in functionalis support proliferating and degenerating lymphatic vessel cycle synchronized with the menstrual cycle of endometrial arteries to maintain adequate fluid leakage.

Cyclic Changes of Lymphatic and Venous Vessels in Human Endometrium

Context: Cyclic changes of endometrial arteries are well established but possible cyclic changes of lymphatic and venous vessels have not been fully documented. There are no published morphological reports to support cyclic changes of endometrial lymphatic and venous vessels. Objective: Using cryosections of human endometrium, this study aimed to unveil possible cyclic changes of lymphatic and venous vessels. We previously reported cyclic changes of lymphatic vessels in human endometrium using D2-40. Design: A total of 16 cases representing menstrual, proliferative and mid and late secretary phase were studied. For Immunocytochemical staining, lymphatic vessel endothelial hyaluronan receptor 1 and von Willebr and factor were used for lymphatic and venous vessels, respectively. We used polyclonal LYVE-1 in this study, which revealed more lymphatic vessels than using D2-40. Results: Residual lymphatic and venous vessels were present in menstrual basalis. In Day 5 - 9 endometrium, there were sparse lymphatic vessels but were numerous growing venous vessels in thin proliferating functionalis. In Day 14 - 22 endometrium, there were scattered lymphatic vessels and numerous venous vessels in functionalis. In Day 25 - 26 endometrium, there were many dilated lymphatic vessels and numerous dilated, disintegrating venous vessels in upper functionalis than lower functionalis. Conclusion: The above findings support that lymphatic vessels are sparse but venous vessels are numerous in early proliferative functionalis. Lymphatic vessels grow from basalis to thin functionalis. In premenstrual phase, lymphatic vessels proliferate from lower to upper functionalis, and both lymphatic and venous vessels disintegrate for shedding by this immunocytochemical study using lymphatic and venous markers. Thus, all lymphatic, venous and arterial vessels undergo menstrual cyclic changes and shed for menstruation.