PULMONARY INTRAVASCULAR MACROPHAGES IN DEER

Pulmonary intravascular macrophages (PIMs) have been found in the sept al capillaries of deer lungs. Lung samples from adult deer were fixed in 2.5% glutaraldehyde, and then routinely processed for electron micr oscopy. The main features of the PIMs were the presence of tubular inv aginations in the membrane (micropincytosis vermiformis), phagosomes, and junctions with endothelial cells. A mean of 4.4 of these junctions was recorded per cell. They comprised segments ranging from 67 to 289 nm in length, where the plasma membranes were separated by spaces fro m 10 to 25 nm wide. In these areas the cytoplasm underlying the membra nes showed evidence of increased electron density. When PIMs were comp ared with alveolar macrophages, it could be seen that although the PIM s were more numerous (more than twice), they were also smaller than th e alveolar macrophages (47.625 versus 101.260 mu m(2) respectively).