HISTOLOGICAL AND HISTOCHEMICAL FEATURES OF ENDOMETRIAL BLOOD VESSELS AT THE EMBRYO IMPLANTATION SITE IN SPONTANEOUS MISCARRIAGE

Abstract

Pregnancy loss is observed in approximately 20–25% of all pregnancies, and there is currently no tendency toward a reduction in its frequency. In early gestation, the mechanisms leading to miscarriage are associated with activation of the hemostatic system. A key role is played by endothelial dysfunction, which contributes to the development of placental infarctions. Aim. To establish histological and histochemical features of the blood vessels of the endometrium at the site of implantation of the oosperm in case of spontaneous miscarriage. Materials and methods. Pieces of the endometrium in case of spontaneous miscarriage during period of 6–12 weeks of gestation have been studied using histological and histochemical methods, that is 24 observations. Serial paraffin sections 5 microns thick have been stained with hematoxylin and eosin for the review, with Bromophenol Blue according to Mikel Calvo – in order to study the processes of oxidative modification of proteins, with chromotrope-water blue according to N. Z. Slinchenko – in order to determine the state of collagen of subendothelial basement membranes. Perls's method for iron has been used in the cases of the required differentiation of hemosiderin and lipofuscin. Histological and histochemical specimen have been studied in a light-optical microscope Delta Optical Evolution 100 (planachromatic lenses) in transmitted light. With the help of this microscope and digital camera OlympusSP-550UZ the digital copies of the image have been received. Results. In histological sections of the endometrium at the implantation site of the embryo at 6–12 weeks of gestation, arteries, arterioles, veins, venules, and capillaries were identified, typical for this gestational period. Quantitative analysis showed a predominance of arteries (48.4 ± 0.12%) and veins (41.1 ± 0.11%), totaling 89.5 ± 0.18%. Arterioles accounted for 4.8 ± 0.05%, venules – 3.9 ± 0.04%, and capillaries – 1.8 ± 0.02%. A significant proportion of vessels showed endothelial desquamation: arteries – 36 ± 0.10% (most pronounced in those with early fibrinoid necrosis, observed in 8 of 24 women, 33.3%), and veins – 40 ± 0.13%, including complete endothelial denudation. Non-desquamated endothelium was morphologically unremarkable, except for the presence of a golden-brown pigment (identified as lipofuscin) in the endothelium and occasionally in the perivascular area. Mean R/B ratios were highest in venous endothelium, lower in arteries, and lowest in arterioles, venules, and capillaries. Using N. Z. Slinchenko’s histochemical method, changes in the subendothelial basal membranes were observed only in arteries with fibrinoid necrosis, manifested as complete destruction of the membranes at necrotic sites. Summary. In the endometrium in case of spontaneous miscarriage the sections of arteries and veins dominate, which are respectively 48,4±0,12% and 41.1±0,11% (together 89.5±0,18%), the sections of the arterioles occur with a frequency of 4,8±0,05%, venules – 3.9±0,04% and capillaries – 1,8±0,02%. The arteries of the endometrium show a high level of endothelium desquamation processes, a high level of oxidative protein modification processes, and in one third of cases, fibrinoid necrosis of individual arteries with destruction of subendothelial basement membranes. The veins of the endometrium have a high level of endothelium desquamation processes and a high level of oxidative protein modification (even greater than in the arteries).