Development of the Heart of the Giant South American River
Turtle, Podocnemis expansa (Testudines: Podocnemididae)
Amazon Turtle; Podocnemis expansa; embryology; circulatory system.
The septation of the cardiac ventricle of turtles is remarkably different from that in mammals and birds. The ventricle is partially divided by two incomplete septa in three subchambers. The origin of the development of this septation is not yet fully understood. There is controversy over the homology of cardiac chambers and septum components and how this pattern of chelonians was modified to the complete septum in mammals, birds and crocodiles. Cardiac ventricular septation is of great interest for phylogenetic understanding, but it is also crucial for understanding many types of cardiac defects in mammals. The aim of this work was to evaluate the embryonic development of the heart of the Amazonian turtle, Podocnemis expansaspecies. The material was collected on two artificial beaches near the Balbina hydroelectric power station in the Uatumã River bed of Amazonas, constructed by the Center for Preservation and Research of Aquatic Chelonia (CPPQA) from September to December 2014. Twenty-six embryo / fetus hearts were collected throughout the incubation period until hatching (62 days). The hearts were fixed in 4% paraformaldehyde in phosphate buffer for histological processing for paraffin inclusion and light microscopy analyzes. Meanwhile, seven newly hatched hearts were fixed in 2.5% glutaraldehyde and submitted to Scanning Electron Microscopy (SEM) processing. Studies such as this allow us to know a little more about the development of the reptilian heart and help elucidate important aspects of cardiogenesis in vertebrates.