title: Fine structure and endocytic properties of subendothelial macrophages in the bulbus arterious of two bony fish species.
abstract: The ultrastructure and endocytic properties of the subendothelial macrophages in the bulbus arteriosus of 2 teleosts, Cichlasoma severum and Xiphophorus helleri, are described. These cells show a diameter of 6 to 10 microns and contain a number of membrane-bound inclusion bodies, which vary greatly in size, shape, and electron density. Frequently, these bodies display myelin figures. Further, in the peripheral part of the cell there regularly occur bristle-coated vesicles. In specimens of X. helleri, injected intraperitoneally by a ferritin solution 20 to 400 h before the sacrifice, the subendothelial macrophages in the bulbus arteriosus contain large, ferritin-packed lysosomes. Similar inclusions were also seen in monocytes in the bulbar lumen. In the bulbus arteriosus of C. severum, there regularly occur mast cells beneath the endothelial lining, whereas the bulbar tissue in X. helleri lacks such cells. The present results are discussed and compared with those reported previously on the fine structure of free macrophages in mammals.
mesh_terms: D000818:Animals; D004705:Endocytosis; D005399:Fishes; D006321:Heart / Q000502:physiology*; D008264:Macrophages / Q000502:physiology / Q000648:ultrastructure*; D008854:Microscopy, Electron; D009206:Myocardium / Q000648:ultrastructure*; D013045:Species Specificity