Distribution and Structure of Purkinje Fibers in the Heart of Ostrich (Struthio camelus) with the Special References on the Ultrastructure

Abstract

Purkinje fibers or Purkinje cardiomyocytes are part of the whole complex of the cardiac conduction system, which is today classified as specific heart muscle tissue responsible for the generation of the heart impulses. From the point of view of their distribution, structure and ultrastructural composition of the cardiac conduction system in the ostrich heart were studied by light and electron microscopy. These cells were distributed in cardiac conducting system including SA node, AV node, His bundle and branches as well as endocardium, pericardium, myocardium around the coronary arteries, moderator bands, white fibrous sheet in right atrium, and left septal attachment of AV valve. The great part of the Purkinje fiber is composed of clear, structure less sarcoplasm, and the myofibrils tend to be confined to a thin ring around the periphery of the cells. They have one or more large nuclei centrally located within the fiber. Ultrastructurally, they are easily distinguished. The main distinction feature is the lack of electron density and having a light appearance, due to the absence of organized myofibrils. P-cells usually have two nuclei with a mass of short, delicate microfilaments scattered randomly in the cytoplasm; they contain short sarcomeres and myofibrillar insertion plaque. They do not have T-tubules.

Intramural conduction system gradients and electrogram regularity during ventricular fibrillation

“…Though past research has suggested the possibility of more active conduction in the left ventricle, our research seemed to indicate no significant difference between the two regions [[12], [13], [14],31]. This is in keeping with the other results of this study, given that Purkinje fibers are present in both ventricles [15,32].…”

Does the right muscular atrioventricular valve in the avian heart perform two functions?

“…Indirectly, the argument in favor of this opinion is the fact that thickening of the MV occurs when RV hypertrophy is developed in birds (Pees et al, 2001;Stedman and Brown, 2002;Pees et al, 2006). One more reason for this opinion is the presence of conducting myocytes in the MV (Davies, 1930;Prosheva, 1986;Lu et al, 1993;Parto et al, 2013). As it is known, mainly the conduction system is responsible for the excitation pattern in the heart of endothermic animals.…”

“…Later, the presence of conducting myocytes in the avian MV was proved by electrophysiology and electron microscopy (Prosheva, 1986;Lu et al, 1993;Parto et al, 2013).…”

Morpho‐functional characterization of the heart of Gallus gallus domesticus with special reference to the right muscular atrioventricular valve

“…; Parto et al. ; Prosheva & Kaseva, ). As known, conducting myocytes are mainly responsible for the excitation pattern in the heart ventricles of endothermic animals.…”