Cyclic Changes of Lymphatic and Venous Vessels in Human Endometrium

Abstract

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.

Immunohistochemical Staining for Lymphatic and Blood Vessels in Normal Tissues: Comparison between Routinely Paraffin-Embedded Tissues and Frozen Sections

“…Rogers et al concluded that lymphatic vessels in functionalis were significantly reduced compared to basalis across the menstrual cycle (58)(59)(60)(61). Their photomicrographs showed weakly immunostained lymphatic vessels in the small, limited tissue areas using D2-40 and VEGF-C as lymphatic vessel markers (58-62), which were not to the same degree of staining reported by us using frozen sections (63,64). These photomicrographs appeared to be taken from the much limited, selectively cherry-picked, positively stained tissue area since there were no large, overview photos of lymphatic vessels at a lower magnification (58)(59)(60)(61)(62).…”

“…Using LYVE-1 as a lymphatic vessel marker, we proved that there were also cyclic changes of lymphatic vessels in the endometrium in the menstrual cycle where there were few or no lymphatic vessels in the early proliferative phase functionalis. In contrast, lymphatic vessels proliferated in the later secretory phase, growing from basalis to functionalis, which dilated and burst in accord with blood vessel bursting during menstruation (63,64). Thus, the frozen section immunocytochemical staining has validated this method's superiority over paraffin-embedded sections for studying lymphatic and blood vessels.…”

Cyclic Changes of Nerve Fibers in Human Endometrium

“…Using routinely formalin-fixed and paraffin-embedded tissues, Boker et al reported 90% of uteri with endometriosis showing more nerve fibers, which were not homogeneously distributed and the degree of immunostaining was the best with rabbit PGP 9.5, followed by rabbit NPY, monoclonal CGRP, rabbit SP and rabbit VIP but no immunostaining by monoclonal NF using alkaline phosphatase for detecting method [6], as we used in this study. Our immunostaining with cryosections produced more homogenous and diffusely distributed nerve fibers in functionalis, basalis and myometrium (Figures 1-3), which proved to be a better and superior staining than the routinely paraffin-embedded tissues for nerve fibers, lymphatic vessels and venous vessels [8] [9]. Both Boker et al and Tokushige et al used neural markers for sensory C, Aδ, adrenergic and cholinergic nerve fibers in the functionalis with several nerve markers including PGP 9.5, NF, substance P, vasointestinal polypeptide, neuropeptide Y and calcitonin gene-related peptide [6] [22] [23].…”

“…Thus, more reports support the presence of nerve fibers in normal functionalis in addition to basalis and myometrium [6] [7]. All the previous immunocytochemical studies had been performed with routinely formalin-fixed and paraffin-embedded tissues [2]- [6], which may not detect all nerve fibers whereas frozen section immunocytochemistry revealed consistent presence of lymphatic vessels [8] and venous vessels [9] in endometrium from normally cycling women. The current study aimed to detect the presence of nerve fibers in normally cycling endometrium of different menstrual cycle using NF and CD 56 immunostaining in basalis, functionalis and myometrium.…”

Uterine Fibroids (Leiomyomata) and Heavy Menstrual Bleeding

“…Microradiographic studies in the 1970's supported the notion that HMB resulted not from the fibroid vasculature itself but rather from venous lakes dilated and enlarged by virtue of increased interstitial pressure from the growing tumors ( 88 ). Once corrosion cast microscopy methods became available, studies into vascular changes within the myometrium in the presence of uterine fibroids indeed found venous lakes enlarged in uteri bearing fibroids in comparison to normal uteri ( 89 ), and further support to the theory was lent by immunohistochemistry studies of cyclic changes in uterine vasculature showing dilated and disintegrating venous vessels in the upper functionalis layer of the endometrium ( 90 ), showing that menstrual blood was largely venous in origin. However, the notion that physical pressure was the main factor leading to enlarged venous lakes was challenged once molecular biological analyses of angiogenic factors were able to show that indeed growth factors were largely responsible for the enlargement of veins and venous lakes ( 91 ), and that the heavy bleeding resulted from a failure of the fibrin/platelet plugs formed in the coagulation cascade in closing these blood vessels of increased diameter successfully.…”