Issue: 2024, Vol. 29, No. 2

I. S. Sesorova. A. V. Zaitseva, P. S Vavilov, T. E. Kazarova

FUNCTIONAL FEATURES OF ENTEROCYTE ULTRASTRUCTURE OF INTESTINAL VILLI IN RATS IN THE FIRST DAY AFTER BIRTHI

Keywords

intestinal villi, enterocytes, newborn, lipid overloading, transcytosis, Golgi complex

Abstarct

Despite the widespread use of artificial nutrition in neonates, a detailed understanding of the functional features of the intestinal villi structure in the first day after birth is currently insufficient. Objective – to study the functional features of the enterocyte ultrastructure of the intestinal villi of newborn rats before the beginning of feeding and the transport pathway of lipids through the enterocyte after the first feeding. Material and methods. The initial section of the small intestine of Wistar rats was studied on the first day after birth: 30–40 minutes after birth before suckling and after feeding. The structures of secretory and endocytosis pathways of enterocyte of intestinal villi were analysed by transmission electron microscopy and electron microscopic tomography. Results and discussion. Apical endocytosis and a well-developed apical tubular-vesicular endosomal network were found in enterocytes of newborn rats. Morphological evidence of lipid transport via the secretory pathway in newborn rats prior to feeding was obtained, as evidenced by a functionally active Golgi complex (CG). During the first day after birth, lipids in the intestinal villi of newborn rats are transported by endocytosis and a state of overload of the secretory pathway at the ER-Golgi complex site is observed. This leads to the accumulation of lipid droplets in the cytoplasm of the enterocyte and their fusion in part of the cells with the formation of giant lipid "lakes". Specific changes in enterocytes of newborn rats after the first feeding are similar to those described earlier in sexually mature rats after a large lipid load. Con- clusion. The beginning of feeding in newborn rats causes in intestinal villi a situation of excessive lipid load and accumulation of giant lipid droplets in the cytoplasm of enterocytes, which can lead to collapse of the transport pathway and cessation of the absorptive function of the epithelium.

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• Vestnik2_2024-39-44