Abstract
A total of ten male Egyptian bovine (Bos aegyptiacus) of 1-10 years old were used to describe the histological changes of the heart ventricles with special reference to Purkinje fibers. The bovines were divided into three groups according to age; immature, mature and adult animals. The histological sections from all examined animals’ groups revealed three different layers of the wall of both right and left ventricles; endocardium, myocardium and epicardium. The endocardium was lined with endothelium and filled with fibrous connective tissue. The endocardium of adult bovine was the thickest. Purkinje fibers appeared of pale cytoplasm with few myofibrils. They were present in the deep layer of endocardium and in the myocardium. The size of Purkinje fibers and the amount of their myofibrils appeared to be increased with advanced age. Bundles of cardiac muscles were the main constituent of the myocardium. The myocardial bundles were separated by fine connective tissue in immature animals that showed an increased amount in the adult animals. The hypereosiophilic cardiac muscle cells were observed in the ventricles of both mature and adult animals suggesting hypercontraction during rigor mortis. An external layer of the ventricles was the epicardium which consisted of connective tissue and covered with mesothelium. Overall, this study revealed histological changes in the wall of the ventricle and Purkinje fibers of Egyptian bovine (Bos aegyptiacus) in relation to age. Additionally, the hypereosionophilia of the cardiac muscle cells was recorded in the ventricles of mature and adult bovine.

Key words: Bovine; Histology; Heart; Purkinje fiber; Ventricle