[The comparative morphology of the specific endothelial granules in the microvessels of the hypertrophied myocardium in patients with congenital heart defects and in experimental animals].

Specific endothelial granules of myocardial microvessels were studied in both patients, suffering from different congenital heart pathology, and dogs, before and during hyperthermia. In the intact myocardium of dogs we found two morphological varieties of granules, dark and light ones. The ultrastructural polymorphism of these granules was due presumably to hyperthermia. In cases of heart disease, a third morphological form of granules was revealed in the endothelium of myocardium microvessels in the hemodynamic overloaded heart compartments. These granules were larger and had a lighter matrix and a lesser amount of tubes. The granules are considered to be ultrastructural characters of structural reconstruction in the wall of hypertrophied myocardium microvessels at the endothelial level.