Ultrastructure of nuclear compartment in cardiomyocytes during regenerative and plastic insufficiency of the myocardium

Abstract

We studied ultrastructure of nuclear compartment in cardiomyocytes during regenerative and plastic insufficiency of the myocardium induced by anthracycline antibiotic daunomycin. A peculiarity of ultrastructural organization of cardiomyocyte nuclei under these conditions is almost complete disappearance of the heterochromatin lumps. The earliest changes in nucleoli under conditions of disturbed DNA-dependent RNA synthesis are segregation of the granular and fibrillar nucleolonema components. Deep alterations in the nucleoli manifested by fragmentation and annulation correlate with pronounced changes in cardiomyocytes ultrastructure, intensive lysis of the myofilaments, reduction of the organelles, and enhanced autophagocytosis.