[Interaction of microorganisms with host cells during phagocytosis]

All cells, including epithelial cells, are endowed with the capacity to absorb foreign particles. Differences in ultrastuctural changes, identifyed following phagocytosis of various pathogens and non-living particles, are rather of a quantitative than of qualitative character-they manifest themselves first of all in various time periods of development of a cytopathological reaction. At early stages of the interaction it is hardly possible to detect any difference between virulent and avirulent microorganisms, colloid and even inorganic particles. In later periods the difference is quite evident. Namely, the phagocytic particles, which are rapidly destroyed by the host's cell or stay therein for a long time undergoing slow destruction, are contained in vacuoles and are isolated from cytoplasm by one- or two-layer membrane; virulent microorganisms and cytotoxic particles, which rapidly destroy the cell themselves, in most cases lie loosely in the cytoplasm, and at the same time diffuse lesion of the membrane systems of the cell is noted.