Left Atrium of the Mature Dromedary Camel Heart (Camelus dromedaries): Microanatomy

Abstract

The current work was carried out on the left atrium of ten healthy mature camels. The specimens were collected and examined histologically after being fixed in 10% Neutral Buffered Formalin. The atrium was processed till paraffin sections obtained and stained. Microscopically, the left atrium is consisted of three major tunics; the internal endocardium, the middle myocardium, and the external epicardium. The endocardium is the inner layer of the atrial wall and consisting of the endothelial layer of simple squamous epithelium that lining the atrium, subendothelial layer of loose connective tissue supporting the endothelium and the subendocardial layer that connecting the endocardium with the myocardium. Myocardium is the middle layer of the atrium, forming the main mass of the atrial wall. It is sandwiched between an outer epicardium, that covers the atrium, and an inner endocardium, that lines the atrial chamber. It is mainly formed from bundles of the contractile cardiac myocytes; myocardiocytes that arranged in strands or branching columns. The left atrium is externally covered with the epicardium that is relatively thin in comparison with the myocardium and consisting of a subepicardial layer of highly vascularized loose connective tissue and the mesothelium of simple squamous epithelium.