Histological features of the mitral valve in Anglo‐Nubian goats

Abstract

The mitral valve, also known as the left atrioventricular valve, is located in the left side of the heart between the left atrium and the left ventricle. The valve structures are involved in the completion of the pulmonary circulation and contribute to the continuous circulation of blood in the animal's body. Knowledge of the valve leaflets' histological features in the breed aspect allows the most accurate and individual approach to diagnosing, preventing, and treating cardiac pathologies. Our study aims to research the histological features of the left atrioventricular valve structure in the Anglo‐Nubian goats. The material for the study was ten corpses of Anglo‐Nubian goats aged from one to two years. The material was fixed with a 10% formalin solution for 24 hours, and then it was paraffin‐embedded. The prepared sections were stained with hematoxylin and eosin. The mitral valve of the Anglo‐Nubian goats has anterior and posterior leaflets in its composition, also labeled septal and mural. Each leaflet consists of fibrous plates formed from dense connective tissue with a high amount of cells. The leaflets have three layers in their structure: the atrialis, which faces the left atrial cavity; the fibrosa, which faces the left ventricular cavity; and the spongiosa, which is located between the previous two. The thickness of the atrialis layer of mitral valve leaflets in examined Anglo‐Nubian goats is 175.42±19.0 μm. This layer is characterized by a smooth surface, which is covered with one layer of endothelial cells. Some areas of the histological section are superimposed like scales on top of each other. In contrast to the atrialis, the fibrosa layer has a rough surface due to high outgrowths on it, from which the chordae tendineae begin. The thickness of the layer in the Anglo‐Nubian goats averages 126, 35±16.3 μm. As well as atrialis, fibrosa is covered with one layer of endothelial cells and has a similar histological picture. The spongiosa layer of the mitral valve leaflets is consisting of loose connective tissue. Large amount of glycosaminoglycan is observed on a histological section of this layer. The thickness the spongiosa is 286±46.8 μm. Based on the results of our research, the following conclusions can be drawn: The leaflets of Anglo‐Nubian goats' mitral valve consist of three layers, of which the spongiosa layer is most developed. A large amount of glycosaminoglycan was found on the histological section of the spongiosa layer, which confirms the development of valve leaflets from the cardiac skeleton.