Morfologia do coração de cateto (pecari tajacu linnaeus, 1758)

Abstract

The objective of this study was to investigate the angioarchitecture, shape and location, as well as the mischroscopic aspects of the collared peccary (Pecari tajacu) heart conduction system, using 12 animals, 6 males and 6 females. To establish the topographic parameters of the heart, an incision was made from intermandibular synchondrosis to xiphoid cartilage to remove the sternum. The hearts were removed from which four hearts were immersed in 10% formaldehyde solution for 24h for fixation and subsequently made sections to expose the inner face. Two hearts had their arterial system perfused with yellow Neoprene (650) latex, and two with yellow vinyl acetate, which were later corroded with 20% sulfuric acid for 72h. The whole region containing the angle between the cranial vena cava and the right atrium of two hearts was included in histological paraffin, and fragments from the remaining two to the dorsal portion of the interventricular septum were obtained, stained with hematoxylin and eosin (HE). The analysis of the data showed the heart of collared peccary has an elongated conical shape, occupies most of the middle mediastinal space of the thorax and is located in a region delimited between the 3rd and 6th rib, surrounded by the pericardium, which is connected to the diaphragm by of the frenopericardial ligament. From the aortic arch emerge two collateral branches, the brachiocephalic trunk, which branches into the right subclavian artery and a common trunk of the right and left common carotid arteries and then into the left subclavian artery. In cardiac arterial models the left coronary artery emerged from the aorta, between the left auricle and the pulmonary trunk, and branched into a superficial branch that returns to the left auricle; a circumflex branch which, through the coronary sulcus, circled the base of the heart toward the atrial face; an oblique branch and the paraconal branch, which ran toward the apex. The right coronary artery emerges from the aorta, between the right atrium and the right atrium, then bifurcates into a superficial branch that inserts into the right auricle and the right circumflex branch, which surrounds the right auricle toward the atrial face, where it becomes the subsinuous branch, moving towards the apex, giving the heart a balanced type vascularization. The sinoatrial node of the catheter was found in the region between the cranial vena cava and the right atrium, at the subepicardial level, not involving the entire junction region. It is a thin, unencapsulated structure, surrounded by a dense mesh of loose connective tissue, where one can notice small arteries and ganglion cells. The nodal myocytes are smaller, with an ovoid round shape and less eosinophilic cytoplasm than the atrial myocardium, distributed as intertwined beams without any specific orientation. The atrioventricular node of the catheter is located near the insertion site of the tricuspid valve septal leaflet, in a subendocardial region, and is divided into two zones, a compact zone and a transition zone. The first consists of small round cells, some with transparent perinuclear cytoplasmic zones, fibroblasts and blood vessels; the second presents continuous fusiform cells and is organized as a network, being smaller than the working myocytes.