Abstract

The pulmonary microvasculatures of rats were studied by injection replicas prepared from Mercox. This medium enabled us to easily obtain consistent, stable, and complete injected replicas of the pulmonary vasculature. In order to investigate the three dimensional structures of the tributaries of the bronchial artery, such as the capillary plexus and vasa vasorum, we performed a scanning electron microscopic(SEM) study of the vascular casts, using Mercox CL-2B as a media. The alveolar capillaries revealed hexagonal or pentagonal rings of vascular networks. In some areas, the vascular rings composed a square network, The bronchial tree was supplied by the bronchial arteries which form a coarse capillary extending as far as the terminal bronchioles. Occasionally the capillary plexus was connected with adjacent capillary networks in and around the alveolar walls. The walls of the pulmonary artery revealed only a single layer of the vasa vasorum, but those of the pulmonary vein were surrounded by more complicated and well developed vasa vasorum than the pulmonary arterial side. The mean diameters of the venous vasa vasorum are greater than the arterial vasa vasorum.

• Keywords: Vascular casts;Capillary plexus;Vasa vasorum;Scanning electron microscopy;