Microscopic and ultramicroscopic structure of typical chordae tendineae of the human’s left ventricle bicuspid valve

Abstract

Objective – to determine the features of the micro- and submicroscopic structure of typical chordae tendineae of the mitral valve of the human heart.Materials and methods. This study was made on preparations of 35 human hearts, in particular the chordae tendineae of the bicuspid valves of the left ventricles of children and people of early and middle adulthood using the methods of light and electron microscopy.Results. The study of typical chordae tendineae of the mitral valve leaflets was made using the microscopic method and the method of electron microscopy. The areas where the chordae tendineae diverge from the papillary muscles, the middle third of the chordae tendineae, and the place of attachment of the chordae tendineae to the mitral valve leaflets were studied. Chordae tendineae are covered with endothelium from all sides. A peripheral collagen-elastic layer of loose fibrous connective tissue is localized under the endothelium, along the entire perimeter of the chordae tendineae and it differs in structure in different parts of the chordae at the submicroscopic level. Bundles of densely packed collagen fibers, which are oriented rectilinearly along the chordae, form the core of the chordae tendineae. Bundles of striated cardiac typical muscle cells are localized in areas where the chordae tendineae origin from the papillary muscles. It was found that in the composition of the chordae tendineae of children the cellular component in the fibrous connective tissue predominates during comparing the typical chordae tendineae of different aged people.Conclusions. This morphological study made it possible to obtain new information and to clarify the data that are already known to morphologists on the micro- and submicroscopic structure of typical chordae tendineae of the mitral valve of the human heart. We found that differences in the histological structure are more typical for the areas of origin of typical chordae tendineae from the papillary muscles and areas of their attachment to the leaflets of the mitral valve. The diameter of the core of the chordae tendineae increases and the thickness of the loose peripheral collagen-elastic layer decreases with age. The received data can serve as a theoretical basis for the further comparative morphological and clinical studies of the mitral valve of the human heart. That, in turn, will facilitate to an increasing the level of diagnostic, to improve methods of prevention and treatment of minor heart anomalies, congenital and acquired defects of the valvular apparatus of the heart.