author(s)
S Jaiswal, I Singh, D Mahanta, S Sathapathy, M Mrigesh and S Tamil Selvan

abstract
Present study was carried out on 24 birds of different age groups of Uttara fowl and elucidates age-related changes in the heart through histological, histomormphometrical, histochemical and ultrastructural studies. Atrial and ventricular wall was comprised of inner endocardium, middle myocardium and outer epicardium. Myocardium was the thick layer which composed of striated and branched cardiac muscles cells with centrally placed nucleus. Numerous purkinje fibres and blood vessels present in the connective tissue network of myocardium. Gomori’s method revealed a dense network of reticular fibres between the cardiac muscle fibres. Weigert’s stain gave positive reaction for elastic fibres in atrial wall and wall of blood vessels. Masson’s trichrome revealed positive reactions for collagen fibres in sub endocardial layer. Ultrastructural studies showed the presence of intercalated disc, branching patterns of cardiac muscles cells, supply of coronary vessels on ventricular wall, pectinate muscles folds and endocardial cells projecting towards the luminal surface of atria.