Morphology, organo- and histometric features of the heart and lungs of a sexually mature domestic dog (Canis Lupus Familiaris L., 1758)

Abstract

The cardiovascular system and respiratory organs in animals are interconnected, they perform extremely important functions for the vital activity of the organism, the main of which is gas exchange. Therefore, the study of the cardiovascular system and respiratory organs is an urgent issue of the present. The aim of the study was to morphologically evaluate the macro- and histological structures of the heart and lungs of the domestic dog. Comprehensive morphological methods of research were used: histological, anatomical, organ, histo-, cytometric, and statistical, which provided new data on the peculiarities of macro-, histo-, and cytomorphometric characteristics of the morphological structures of the heart and lungs. The dog heart has a rounded shape, its absolute weight is 167.58±9.46 g (without epicardial fat – 154.22±8.04 g), relative weight – 0.72±0.005%. It was found that cardiomyocytes of the left ventricle had the largest volume, the right ventricle – the smallest, and atrial cardiomyocytes – the smallest. At the same time, the nuclearcytoplasmic ratio of cardiomyocytes of the left ventricle is 0.0224±0.0076, the cardiomyocytes of the right ventricle have a greater value – 0.0275±0.0081 and the atrial cardiomyocytes have the highest value – 0.0367±0.0105. Such ambiguous cytometric parameters of cardiomyocytes are associated with the morphological and functional activity of the myocardial ventricular muscle tissue and its functional features inherent in spontaneous and rhythmic contractions, which result in blood flow through a closed system of vessels. The absolute weight of the domestic dog’s lungs is 201.3±18.4 g, the relative weight is 1.21±0.14%, the ratio of the absolute weight of the left to the right lung is 1:1.33. According to the asymmetry coefficient (1.37:1), the lungs of dogs are of the narrowed-elongated type. The connective tissue stroma of the lungs occupies 59.62±3.4%, the respiratory part – 40.38±2.6%. The data on the morphology of the heart and lungs of the domestic dog, including the results of the study of the macro- and microscopic structure of the organs under investigation, which are presented in the publication, are of great importance for histology and comparative anatomy, and also make a significant contribution to clinical veterinary medicine.