Histological and ultrastructural studies on the coronary artery of adult domestic dog (Canis familiaris)

Abstract

The objective of this work was to study the histological structure of the dog's coronary artery by light and transmission electron microscope (TEM). The coronary artery consisted of three tunics: tunica intima, tunica media and tunica adventitia. The tunica intima consisted of endothelium rested directly on internal elastic lamina without the subendothelial connective tissue layer. The tunica media were composed of smooth muscle fibres interspersed with few elastic and collagen fibres. The tunica adventitia consisted of collagen and elastic fibres intermingled with fibroblast cells; it had vasa vasorum and nervi vasorum. Some histomorphometric measurements were performed and compared statistically. The ultrastructural study showed that the endothelial cells were communicated through complex junctions and characterised by filiform cytoplasmic processes passed through the opening of the underlying internal elastic membrane. The smooth muscle fibres of tunica media communicated with each other through cytoplasmic processes. The tunica adventitia showed minute non-myelinated nerve. This work revealed that the dog's coronary arteries are typical muscular arteries, which show little structural variations from that of other mammals. K E Y W O R D S coronary arteries, dog, histology, transmission electron microscope, tunica intima | 81 KILANY et AL.

Structural Study on the Heart Ventricles of the Domestic Dogs (Canis Familiaris) With Special References to Cardiomyocyte Ultrastructure

“…Histologically, the ventricular wall of the dog heart consisted of the outer epicardium, the middle myocardium, and the inner endocardium as reported in previous studies (3,9,12,17,18). The epicardium was composed of the mesothelium and the subepicardial connective tissue layer.…”

“…The current study indicated that the deep layer of the dog's ventricular endocardium contained bundles of Purkinje fibers. The same results were confirmed in camel (3), cat (9), and bovines (12). These Purkinje fibers were restricted to the dog's ventricular subendocardial layer as revealed in human (22) and dogs (23).…”

“…The epicardium was composed of the mesothelium and the subepicardial connective tissue layer. These findings were recorded partially in camel (3) and bovine (12).…”

“…These Purkinje fibers were restricted to the dog's ventricular subendocardial layer as revealed in human (22) and dogs (23). However, the presence of intramural Purkinje fibers at the depth of the myocardium among cardiac muscle bundles and individual cardiomyocytes was confirmed in camel (3), bovine (12), and sheep (22,24).…”

“…Many studies have been conducted on the histological structure of the heart ventricles of human and different domestic animals (8, 9,10,11,12). However, there are few studies that are interested in the histological structure of the dog's heart ventricles.…”