Lobation and vascularity of the liver in the red-eared slider (Trachemys scripta elegans)

The internal organs of chelonians are exposed to intra-coelomic pressure during limb movement and breathing due to the presence of the shell. Pressure on organs alters the hemodynamics and has functional implications. The chelonian liver occupies most of the cranial portion of the coelomic cavity and can be susceptible to this pressure. The morphology of the liver may thus have adapted to accommodate this condition. We therefore investigated hepatic lobation and vascularity in 13 red-eared sliders. We detected right lateral, ventral, and dorsal lobes, and left ventral and dorsal lobes. These lobes received multiple inflows comprising the hepatic portal vein, a pair of lateral abdominal veins, and the hepato-duodenal, hepatic, and gastro-hepatic arteries. The hepatic portal vein bifurcated into right and left branches, distributing to the right lateral lobe and to the right dorsal, right ventral, left ventral, and left dorsal lobes, respectively. The right and left lateral abdominal veins distributed to the right ventral and left ventral lobes, respectively. All arteries supplying the liver arose from the celiac artery. The hepato-duodenal artery supplied the right hepatic lobes, and the hepatic and gastro-hepatic arteries distributed to the left hepatic lobes. Outflow occurred through the right and left hepatic veins, which drain the right lateral and ventral and left hepatic lobes, respectively. In addition to these veins, veins from the right dorsal lobe drained directly into the caudal vena cava. The multiple inflow and outflow pathways detected in this study may be advantageous in maintaining proper hemodynamics even under coelomic pressure.