Rung-ruangkijkrai T. et al./TJVM 37(3): 51-58. 51 Morphology of the Heart of a White-cheeked Gibbon (Hylobates concolor)

The heart was recovered at post mortem from an adult white-cheeked gibbon, Hylobates concolor, for anatomical and histological studies. Macroscopically, it had oval shape, blunt and spherical apex with 3.5 cm. and 5 cm. in width and length. Smooth edged comma-shaped right auricle was markedly bigger than the jagged-edged left auricle. Pectinate muscles were found both at the internal surface of the right auricle and lateral free wall of the right atrium, while limited only in blind part of the left auricle. The coronary arteries supply was left coronary type. The left coronary artery gave circumflex and paraconal interventricular branches. Subsinuosal interventricular and intermediate branches ramified from the circumflex branch. One septal and two papillary muscles were found in both left and right ventricles. There was only one small trabecula septomarginalis in the left ventricle, but three in the right ventricle. Aortic arch gave off brachiocephalic trunk and left subclavian artery. Ligamentum arteriosum linked between the beginning of descending aorta and the junction between the left pulmonary artery and the pulmonary trunk. Histological results were generally indistinct. However, number of blood vessels observed in the atria was less than in the ventricles. Collagen fibers were the major fiber population of the subendocardium while elastic fibers were confined mainly in the subendothelial layer