No abstract

Reproduction and maintenance of the integrity of the epithelial layer requires a precisely balanced rate of growth and cell death. In overcrowded areas of tissue, some of the cells undergo a consecutive loss of intercellular connections, which leads to a progressive decrease in their number. To keep the barrier intact, the epithelium eliminates dying cells by means of extrusion. Cell extrusion is a unique morphological phenomenon inherent in the epithelium, in which cells prone to apoptosis or non-apoptotic elements are removed from the tissue, thus breaking the symmetry of the layer. During extrusion, the site intended for apoptosis, due to signals from neighboring elements, forms and compresses the ring of the actomyosin complex, which leads to the removal of dying cells from the epithelium. Apoptosis of epithelial cells of the respiratory tract is the main mechanism for a decrease in the cell number after hyperplastic changes in it, arising from exposure to negative factors, viral or bacterial infection. In the review, the authors demonstrate the original photographs of the extrusion of airway epithelial cells.