Lizards and snakes are different to mammals in several aspects of nitrogenous excretion. Uric acid is the primary catabolic end-product of protein, nonprotein nitrogen and purines in reptiles. It is synthesised in the liver and excreted by renal tubular secretion. | Lizards and snakes are different to mammals in several aspects of nitrogenous excretion. Uric acid is the primary catabolic end-product of protein, nonprotein nitrogen and purines in reptiles. It is synthesised in the liver and excreted by renal tubular secretion. |