Morphology of the Heart of Bengal Monitor Lizard (Varanus bengalensis)

Abstract

Topographic relations and gross morphological parameters of the heart were recorded. The caudal one third of the heart was enclosed within the depression of liver. The heart as a whole had elongated profile and was composed of three chambers viz., right and left atria and a common ventricle. The right atrium was bigger than the left one and presented an additional chamber, the sinus venosum. The endometrium of the atria showed pectinate muscles. The right and left atria communicated via the corresponding atrioventricular openings to the ventricle. The septae subdivided the cavity into three sub chambers: cavum pulmonale, Cavum venosum and Cavum arteriosum from right to left in sequence. Microscopically, the compact myocardium revealed muscle fibres oriented in three directions. The interventricular septum was located between cavum pulmonale and cavum arteriosum. Along the upper border of the interventricular septum, the cavum arteriosum communicated with the cavum venosum. Muscular ridge was present on the right of interventricular septum. Muscular ridge along with bulbous lamellae created separation between the cavum venosum and cavum pulmonale. The right aorta was considerably larger than the left. The unique anatomical features recorded in the study support limited mixing of oxygenated and deoxygenated blood within the heart.