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A Morphometric and Ultrastructural Study of the Microvessels of the Functional Zone of Normal Human Endometrium with Some Notions on Possible Secretory Functions of the Endothelial Cells
Author(s) -
Blackwell Peter M.,
Fraser Ian S.
Publication year - 1988
Publication title -
asia‐oceania journal of obstetrics and gynaecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.597
H-Index - 50
eISSN - 1447-0756
pISSN - 0389-2328
DOI - 10.1111/j.1447-0756.1988.tb00100.x
Subject(s) - microvessel , cytoplasm , ultrastructure , endometrium , basement membrane , angiogenesis , endothelial stem cell , vascularity , biology , pathology , chemistry , endocrinology , medicine , anatomy , microbiology and biotechnology , biochemistry , in vitro
A comparative analysis of microvessel concentration in 24 specimens of normal human endometrium has been carried out in the mid‐proliferative ( n = 12) and mid‐secretory ( n = 12) phases of the menstrual cycle, with the finding of a significantly greater vascularity in the mid‐secretory phase (25.0+/‐12.7 microvessels/sq mm compared with 12.2+/‐6.3; mean +/‐SD; p<0.005). No significant difference was observed between the 2 phases in measurements of maximum luminal diameter, mean luminal diameter or luminal area, but there was a significantly greater mean diameter at the basement membrane in the proliferative compared with the secretory phase. This indicates that the microvessel diameter was larger in the proliferative phase due to greater height of the endothelial cells, while luminal size remained constant. Mean area (+/‐SD) of endothelial cell cytoplasm per transverse microvessel section was 58.5+/‐28.6 sq um in the mid‐proliferative phase and 44.9+/‐26.2 sq um in the mid‐secretory phase ( p = 0.001). In a detailed ultrastructural study made of all the microvessels seen in 12 specimens of normal endometrium (6 mid‐proliferative and 6 mid‐secretory), the morphological appearance of the microvessels varied widely, especially with respect to cytoplasmic density and organelle concentration. Three distinct types of endothelial cell junction were observed each of which would impart a different level of cohesion to the vessel. A proposal is put forward that the presence of very weak junctions may be a factor leading to a propensity for excessive menstrual bleeding in some women. Endothelial cells have been shown by others to be highly metabolically active and secretory in nature and it has been assumed that they externalise their products by exocytotic secretory mechanisms. We have described unusual projections from the luminal membranes of human endometrial endothelial cells and free membrane‐bound luminal bodies observed in over a quarter of all endometrial microvessels. The function of these projections and bodies is unknown, but their appearances are consistent with the hypothesis that they represent a form of apocrine secretion with release of cytoplasmic material into the microvessel lumen for local and distant use.