Macrophages are the key cells for invading and replication of mycobacteria in the host and they play principal role in the pathogenesis of the tuberculosis. The aim of the present study was to reveal if mycobacterium invade other cells except these of immune defense and macrophages fi rst of all as a common feature. The results of ultrastructural studies of lungs of Mycobacterium bovis intraperitonealy infected rabbits and livers of Mycobacterium avium subcutaneously infected chickens showed the presence of mycobacteria into the cytoplasm of pneumocytes II type and capillary endothelial cells of rabbit lungs as well as in the cytoplasm
of chicken liver parenchyma cells. On the base of these results and in particular invading of pneumocytes II type as a producers of the surfactant it was suggested that the surfactant or some of his components likely enhance phagocytosis of mycobacteria by macrophages. It could be a reason for mycobacterium affi nity to invade pneumocyte II type and to manipulate quality and quantity of the surfactant or some of his components. These results show that M. bovis invaded pneumocytes II type in vivo and it is an important
step may be in the investigation of the possibility role of these cells in the pathogenesis of lung infection.
