Structure of the heart wall and existence of the blood cells in the heart of the dog-faced water snake Cerberus rynchops (Schneider, 1799)

Abstract

A plurality of investigations on the heart structure of reptiles has been extensively reported; however, it has yet to conduct studies in Cerberus rynchops, the so-called common estuarine water-snake. In this current study, we histologically started to examine the heart wall of the atrium, ventricle chambers, and study the existence of the blood cells in the heart of sexually mature females. The selected samples were those C. rynchops from the Paknam Pranburi Estuary in Thailand using accurate histochemical techniques. The results showed that the heart structure of C. rynchops consisted of three primary compartments (sinus venosus, atrium, and ventricle). All compartments were surrounded by the heart wall, which was typically classified into three layers (the epicardium, the myocardium, and the endocardium), as likely seen in underlying patterns of reptilian heart. In particular, the myocardium of the ventricle in this snake was the thickest layer of the heart wall. Major components of the cardiac muscle fibers in the myocardium with green/ pinkness colors were associated with Massonʼs trichrome and Periodic Shift reagent methods, indicating to present various fibers and glycoproteins. Consequently, several blood cells were also detected in different areas. The normal and atretic red blood cells were seen in the cardiac fluid, as referred to the fluid inside the heart sac, whereas the mast cell was also observed in the heart wall especially myocardium.