[Ultrastructurometric study of the reaction of the enterocyte microvilli in the rat small intestine in natural feeding].

A study was made of the time-course of changes in the length of the microvilli at three main sites of the rat small intestine after natural feeding with a mixture of milk, bread and sunflower seeds. The length of the microvilli during fasting was shown to be maximal in the upper third of the villi and minimal in the apical pole of the villi. After feeding the microvilli experienced shortening which was least marked in the ileum. The morphometric parameters of the microvilli response in enterocytes of the intestinal parts under test are provided depending on their location on the villi. Actomyosin complex of the microvilli was found to take an active part in absorption. The findings confirm the hypothesis of the pinocytic mechanism by which the nutrients are absorbed.