Ultrastructural features of the capillaries,alveolar epithelium,and macrophages of the lungs in germ-free rats

The ultrastructural features of certain components of the lung tissues were studied in germ-free and ordinary rats. The lumen of the capillaries in the lungs of the germ-free rats was smaller than in ordinary animals, and the grossly dilated microvessels found in the lungs of ordinary rats were totally absent. Many mitochondria of the alveolar epithelial cells in the lungs of the germ-free animals differed from mitochondria of ordinary rats in their larger size, and the arrangement of the thickened cristae. A study of the alveolar macrophages in the germ-free rats showed that primary lysosomes were more numerous than secondary. The ultrastructural, features distinguishing the lung tissue of germ-free animals thus revealed were associated with components involved at the subcellular level in the response of the host to microbial action.Institute of Normal and Pathological Physiology, Academy of Medical Sciences of the USSR, Moscow. Research Laboratory of Experimental Biological Models, Academy of Medical Sciences of the USSR, Moscow Region. Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 78, No. 11, pp. 114–117, November, 1974