Pathophysiology of the Blood Vascular Barrier

Abstract

Alterations in the blood capillary wall were studied in the living mesentery of different animals following micro-injury. An attempt was made to determine the particular structural component associated with the various aspects of the injury reactions. Some evidence exists for an endocapillary layer at the endothelial cell-blood interface and/or the inner aspect of the basement membrane. The adhesive phase of the reaction presumably involves one or both of these interfaces through the activation of blood clotting mechanisms. Endothelial cells are potentially capable of phagocytosis and it is suggested that the ultrastructural vesicles are part of this mechanism. Changes in the porosity of the capillary or venular barrier may develop as a consequence of swelling of endothelial cells, as well as of the basement membrane. The capillary wall is shown to be a labile structure in a continuous state of flux. The relation of the endothelial cells to the elaboration and maintenance of the basement membrane represents an important area of homeostasis.