The Cardiovascular Anatomy of the Green Iguana ( <i>Iguana iguana</i> ): Heart Structure, Major Vessels, and Coelomic Circulation

The green iguana (Iguana iguana) is a neotropical lizard with ecological significance due to its role in seed dispersal. Detailed anatomical studies of the circulatory system of this species remain scarce. The aim of this study was to describe the heart, major blood vessels, and coelomic circulation in this species. Four male and two female cadavers were received from environmental authorities, preserved with soft embalming techniques and injected with latex injection. The sinus venosus, positioned dorsally, lacked internal septa and drained into the right atrium via a bicuspid sinoatrial valve. The ventricular sub chambers-cavum arteriosum, cavum venosum, and cavum pulmonale-demonstrated a spatial distribution distinct from other squamates, with the cavum arteriosum and cavum venosum predominantly occupying the left side of the heart. A muscular crest within the ventricle facilitated additional separation between oxygenated and deoxygenated blood, enhancing circulatory efficiency. The aortic and pulmonary trunk valves were identified as simple bicuspid structures. The right aortic arch originated both carotid trunks. The aorta originated multiple parietal, mesenteric, and renal arteries, exhibiting inter-individual variability. A remarkable vascular plexus at the duodenal bulb was observed, from which the hepatic artery originated. The ventral abdominal vein connected the pelvic region to the hepatic portal system. The absence of lateral abdominal veins supports the recommendation to avoid drug administration in the pelvic limbs and tail to prevent renal or hepatic first-pass effects. These findings provide essential information for clinical applications, including surgical interventions and diagnostic imaging in reptile medicine.