The endometrial capillaries during the normal menstrual cycle: a morphometric study

Abstract

The areas of the capillary lumen, the entire capillary, the endothelial cells and the adventitia, as well as the thickness of the endothelial cell layer and the adventitia were studied using morphometric methods in endometrial samples from 34 fertile women who had a hormonal profile compatible with normal ovarian function. The biopsies were grouped around the luteinizing hormone surge. The results were calculated as mean values of 72-h periods and related to the mean levels of oestradiol and progesterone circulating in plasma 72 h prior to the biopsy. The results indicated that the sub-epithelial capillary plexus of the human endometrium undergoes dynamic changes during the normal menstrual cycle with a significant dilatation of the vessels during the post-ovulatory phase. A significant correlation was found between the area of the capillary lumen and the mean level of progesterone circulating in the plasma 72 h prior to the biopsy (P = 0.037). We conclude that the ovarian steroids produced during the normal menstrual cycle are likely to influence sub-epithelial vascularization causing dilatation in the post-ovulatory phase. This dilatation of the sub-epithelial capillaries may be related to the development of oedema appearing in the stroma at the time of the expected implantation. The possible functional significance of the capillary dilatation in terms of implantation, however, needs to be further investigated.

Comprehensive expression analysis of prostanoid enzymes and receptors in the human endometrium across the menstrual cycle

“…These events are characterized by an increase in endometrial capillary dilation, permeability, stromal edema, blood flow, leucocyte number and secretion of pro-inflammatory factors (Fraser et al ., 1987; Johannisson et al ., 1987; Peek et al ., 1992). Pro-inflammatory enzymes PTGS1 and PTGS2 are key mediators of these inflammatory processes.…”

“…The expression of the prostanoid receptors PTGER2, 3 and 4 peaked during the mid-secretory phase. The increased expression of these receptors coincides with increased stromal oedema, blood vessel permeability and endometrial blood flow in the human endometrium (Fraser et al ., 1987; Johannisson et al ., 1987; Peek et al ., 1992). Evidence supporting a role for PGE 2 receptors in these events is demonstrated by infusion of PGE 2 into rodent uteri which has been shown to increase uterine vascular permeability, uterine extracellular fluid volume (Hamilton and Kennedy, 1994) and act as an immunomodulator inhibiting lytic activation of maternal leucocytes (Parhar et al ., 1989).…”

Tumour necrosis factor-alpha (TNF-alpha) in human endometrium and uterine secretion: an evaluation by immunohistochemistry, ELISA and semiquantitative RTPCR

“…Chen et al (1995), described the stimulation of prostaglandin release in cultured human luteal phase endometrial cells by TNF-α. It can be speculated that the increase of endometrial vascular permeability by prostaglandins could have an effect on the implantation process (Peek et al, 1992). An effect of endometrial TNF-α on the preimplantation embryo is only possible if the blastocysts have been proven to express TNF-α receptors and if TNF-α is secreted into the uterine secretion.…”

Altered extent, pattern and characteristics of microvascular density are indicators of neoplastic progression in the endometrium

“…The female genital tract is a notable exception, with angiogenesis being an essential part of the normal endometrial cycle 13, 14. It is characterized by rapid endometrial growth during the proliferative stage, significant growth of spiral arterioles in the secretory stage and coiling and repair of the vascular bed during menstruation 15, 16, 17, 18. This complex process involves the proteolytic degradation of extracellular matrix, proliferation and migration of endothelial cells and ultimately the formation of patent capillary tubules 12, 19.…”