Histological and Histomorphometrical Characterization of the Cardiac Architecture in Pre-natal Non-descript Sheep (Ovis aries)

Background: Being the vital organ of circulatory system, the development of the heart before birth must be studied to safeguard the animal from the incidence of various developmental anomalies. The histological and histomorphometrical details of cardiac architecture especially in pre-natal sheep have not yet been reported. Methods: The foeti of sheep were collected from the local slaughter houses situated at Laxmisagar and Jadupur of Bhubaneswar city. The collected foeti were divided into three age groups viz. early prenatal (up to 50 days) or G-I, mid prenatal (51-100 days) or G-II and late prenatal (101 to 150 days) or G-III. The heart samples of the sheep foeti were processed by routine paraffin technique and after section cutting, the slides were stained by routine Haematoxyline and Eosin stains, Masson’s trichrome stain, Verhoeff’s stain and Gomori’s stain for studying the detailed histological and histomorphometrical parameters. Result: It was revealed that the cells lining the endocardium and epicardium became elongated from flat shape with advancing age. The intercalated discs appeared continuous from broken lines with advancing age in the myocardium of cardiac wall in sheep foeti. The frequency of blood vessels, connective tissue fibres and connective tissue cells increased with age in the subendothelium, subepicardium, myocardium and epicardium in the sheep foeti. The average thickness of heart chambers, average diameter of the myocardiocytes and their nuclei in atrial and ventricular walls, papillary muscles, pectinate muscles and Purkinje fibre cells revealed an age dependent rise in sheep foeti of G-I to G-III. The frequency distribution of myocardiocytes and fibroblast in myocardium also increased with in sheep foeti of G-I to G-III.