The aim of research is to study posthypoxic transformation of the colon wall using light and electron microscopy in an experimental model of rat offspring. Materials and methods. Chronic hypobaric hypoxia at different stages of pregnancy was simulated experimentally in 24 female white mongrel rats using a vacuum flow chamber with a rise to a height of 5000 m at a speed of 25 m/sec for 40 minutes. After delivery, the offspring were examined, subjected to hexenal anesthesia, and then removed from the experiment using decapitation. For light microscopy, resected sections of the small intestine and colon were stained with hematoxylin-eosin, and studied on Topic (Belgium, 2000) and Bio Blue (the Netherlands, 2013). Electron microscopic analysis was performed in a Morgagni 268D transmission electron microscope (FEI, USA). Results. Chronic hypoxia, simulated in the first trimester of pregnancy, led to significant changes in the intestinal mucosa in combination with the growth of the connective tissue component in the muscle layer. The risk of developing dynamic intestinal obstruction occurred in the offspring of all groups, this was supported by an increase in the fibrous tissue of the intestinal wall. Pronounced changes in the microcirculatory bed were detected in animals of groups II and III, as they were predisposed to develop pre-ulcer and ulcerative defects in the wall of the small intestine. At the submicroscopic level, it was detected that both adaptive and destructive processes occurred in the wall ultrastructure of the descending colon of the rat offspring after hypoxic exposure in the prenatal period in animals of all experimental groups. In the microcirculatory bed, there was an increased venous congestion, with the most pronounced changes observed in the third trimester. Conclusion. Thus, the study of hypoxia in the experiment allows investigating more about all the mechanisms of the pathological process and to translate theoretical knowledge into practical medicine.

Based on the analysis of morphological and morphometric data, the clinical and experimental results of the effect of hypoxia on the wall of the small and large intestine in newborns are presented. The clinical part is based on the study of 58 case histories of patients with necrotizing enterocolitis, which the operating material (resected sections of the small intestine, large intestine) was studied in detail. The experimental work included the modeling of chronic hypobaric hypoxia in different trimesters of pregnancy in 4 groups of white rats (24 females). The offspring was taken out of the experiment at 4-5 days after birth, followed by collection of the small and large intestine areas to study histoarchitectonics. It is proved that hypoxia affects the number of newborn offspring, its weight. The small intestine is most vulnerable to the effect of this factor. Analysis of the morphological and morphometric picture of the operating and experimental material convincingly proves that under the influence of hypoxia the destruction of the intestinal mucosa occurs and the growth of the connective tissue component in the muscle layer occurs. Changes from the microcirculation of blood and lymph provoke the development of pre-ulcerative, ulcerative defects and the formation of necrosis. Disturbance of the drainage function promotes the spread of destruction in the intestinal wall.