[The ultrastructural characteristics of specific endothelial granules in the myocardial microvessels in congenital heart defects].

Specific granules in endothelium of microvessels of the right atrium were studied in 15 patients with congenital heart diseases (Fallot tetrad, defect of interventricular septum and aortal stenosis) aged from 3 to 11 by electron microscopy 2 morphological types of granules, varying in optic density-dark and light ones, were found in all observations. Great number of the light granules young forms was also discovered. Maturity of the latter is associated with the increase of number and density of localisation of tubular structures in the granule matrix. Share of granule-containing endotheliocytes varied significantly depending on the kind of the defect (from 27% in aortal stenosis up to 44% in Fallot tetrad), with number of granules varying from 1 to 37 in profile 1. This demonstrates that granule-producing function of endotheliocytes in congenital heart diseases depends on the load exerted on the region, compensating the disturbed hemodynamics in specific pathology and either on presence or absence of hypoxemia.