Epithelioid cells formed in culture of mouse peritoneal cells, stimulated by inactivated Mycobacterium tuberculosis, in a micro-chamber for lifetime observation; 14 days of cultivating. Numerous secretory granules are visible in the cytoplasm of cells. In the culture medium epithelioid cell granules and apoptotic bodies from macrophage are visible. Dystrophic altered macrophages are colored red. A method of interferential contrast in polarized light.