STRUCTURAL STUDY ON THE HEART VENTRICLES OF THE DOMESTIC DOGS (CANIS FAMILIARIS) WITH SPECIAL REFERENCES TO CARDIOMYOCYTE ULTRASTRUCTURE

Abstract: Our study aimed to investigate the light microscopic structure of the dog’s ventricular wall in addition to the fine structure of the cardiomyocytes and the interstitial telocytes. For this purpose, tissue samples from the ventricles of 15 adult domestic dogs (Canis familiaris) were prepared and processed for histological, immunohistochemical, and ultrastructural analysis. The ventricular wall consisted of; epicardium, myocardium, and endocardium. The mesothelium and subepicardial connective tissue layer made up the epicardium. The myocardium was composed of bundles of cardiomyocytes separated by loose connective tissue. The endocardium was lined with endothelium located above the subendothelial connective tissue. Purkinje fibers were found only beneath the subendothelium in the subendocardial layer. The intercalated disc reacted positively to anti-E-cadherin protein. Under the transmission electron microscope (TEM) the ventricular cardiomyocyte appeared enveloped with a scalloped sarcolemma and had a striated sarcoplasm. The nucleus was oval, euchromatic, and centrally located. The mitochondria were multiple and polymorphic located either under the sarcolemma, between the myofibrils, or at the perinuclear pole. At the perinuclear pole, small electron-dense granules were observed. The intercalated disc was made up of desmosomes, adherens junctions, and gap junctions and bound the adjacent cardiomyocytes. Interstitial telocytes with cellular prolongations was evidenced. These interested microscopic structures of the dog’s ventricular wall are expected to help researchers better understand the physiology of the heart ventricles, also provide a control picture that improves the differentiation of ventricular pathological conditions. Keywords: Dog; Heart; Ventricles; E-cadherin; Histology; Electron microscopy.