[Effect of increasing the osmolarity of the extracellular medium on the ultrastructure of vascular smooth muscle cells].

Changes in the structure of the smooth muscle cells of the portal vein are produced by increasing osmotic pressure (osmolarity) in the extracellular medium. It is demonstrated that under the conditions of the experiment intercellular spaces increase, while the number of close intercellular contacts--nexuses--decrease. The number of micropinocytic vesicles in the areas adjacent the membrane increases, cellular processes and deep invaginations on the cellular surface are formed. In some places the basal membrane loses its integrity. The possible role of the morphological changes for functional shifts occurring in the smooth muscle cells of the portal vein under the conditions of increased osmolarity of the extracellular medium is discussed.