[Pathogenesis of cardiovascular disorders in acute experimental arterial obstruction]

Agents producing toxic myocardial effects are shown to appear in systemic blood flow as a result of acute occlusion of aortal trifurcation with subsequent recovery of blood flow in the limbs. The most pronounced effect was noted following blood infusion in dogs whose ischemia of the limbs had lasted for nine hours, instead of twelve, which must be due to specific features of circulation recovery in the ischemic area.

[Scanning electron microscopy of injection replicas of the cardiac microvessels]

The paper concerns three-dimensional study of the organization of the subepicardial network of the blood and lymphatic microvessels of the heart with the aid of scanning electron microscopy of the injected replicas. It is established that the arterioles have regular orientation of the imprints of the nucleus-containing zone of endotheliocytes. The capillaries belonging to the subepicardial network form a thick mesh and are strictly oriented along the muscular bundles. There is no characteristic relief on the surface of the capillaries. The study of the relief of the post-capillary venules made it possible to record different orientation of the imprints of the nuclei-containing zones of endotheliocytes on their surface. The study of structure of "leaks" formed as a result of leaking of resin from the venular segments of the bed enabled one to elicit their passage into the lymphatic capillaries. The latter are represented by flattened tubes, placed over the blood vessels.

[Morphogenic role of the underlying substrate of endothelial and mesothelial cells]

Endothelial and mesothelial cell form, cell surface microrelief and intercellular contacts were studied by scanning electron microscopy. The pattern of the underlying substrate (geometry and expressiveness of basal membrane) is shown to influence the endothelial and mesothelial cell morphology. The morphogenic role of the underlying substrate is discussed.

[Characteristics of the ultrastructural organization of endothelial cells in cardiac and omental blood capillaries based on cryofractographic data]

Using cryofractography, endotheliocytes of heart and omentum blood capillaries were studied, different patterns of distribution of membranous particles being observed of the "P" and "E" faces of the fracture plans of endothelial cell cytomembranes. Three types of distribution of micropinocytotic vesicles can be distinguished: the linear, hexagonal, and the clusteral type. The number of micropinocytotic vesicles was sharply reduced near the region of intercellular contacts. On the fracture plan, attached pinocytotic vesicles look like "craters" on the "E" face, and like circumvallatue papillae on the "P" face. Cell membranes, making intercellular contacts, have a network structure consisting of ridges on the "P" face and of grooves on the "E" face. Such a molecular membrane organization is discussed from the standpoint of modern concepts of the receptor--cytosceletal complex. It is supposed that this complex may control processes of transendothelial mass--transfer.

Mesothelial stomata overlying omental milky spots: scanning electron microscopic study

The presence in the rat omentum of intercellular pores (the classical stomata of von Recklinghausen) between the mesothelial cells overlying aggregates of lymphoreticular cells (the classical milky spots of Ranvier) and the apparent migration of lymphocytes through these stomata were recorded for the first time by scanning electron microscopy. Previous studies on passage of cells across the peritoneum and omentum used experimentally administered cells, while in the present study no cells were administered to the rats and their own lymphocytes were observed in situ. The possible role of lymphocytes in the peritoneal cavity is also briefly discussed.

[Production of injection replicas of microvessels for scanning electron microscopy using resin "PN-8"]

A method for obtaining injection replications of microvessels for scanning electron microscopy using nonsaturated polyether resin PH-8 is described. Possible applications of the method in question to study microcirculatory bed are discussed. With resine PH-8 it is possible to obtain complete and detailed replications which give information on three-dimensional organization both of the microcirculatory bed and of the vascular microrelief peculiarities.

[Study of the rat parotid blood capillaries during a 3-hour feeding cycle]

Regularities attending the change in the lumen diameter and the area of the endothelial cells were studied in the capillaries of the rat parotid gland during the secretory cycle under conditions of circulatory ischemia. The mean lumen diameter and the area of endothelial cells failed to change during the secretory cycle and during the occlusion of the carotid artery. It is thus supposed that enhanced capillary blood flow during the discharge of saliva could be explained by the growing number of the functioning capillaries.