AP BIOLOGY

Detailed explanation-1: -The glomerulus is the network of filtering vessels. Such types of kidneys are seen in birds and mammals also. In reptiles, the metanephric kidneys lie in a more caudal position in the body cavity. Also, they have much larger kidneys with a compact structure containing many tubules.

Detailed explanation-2: -Moreover, the tubular system of the reptilian kidney is continuous from the renal corpuscles to, and including, the ureter. This is quite unlike the mammalian kidney where the tubular system ends in a papilla around which the expanded cup-shaped end of the ureter (renal pelvis) fits (Fig. 1).

Detailed explanation-3: -In reptiles, birds, and mammals, three types of kidneys are usually recognized-the pronephros, mesonephros, and metanephros.

Detailed explanation-4: -The kidneys of reptiles and birds do not follow a similar pattern. It would appear that no one group has the advantage over the other with respect to regulation of the composition of the extracellular fluid because representatives of all groups inhabit a broad range of environments and ecological habitats.

Detailed explanation-5: -In reptiles, there are two pairs of kidneys at birth: the mesonephros and the metanephros. The metanephric kidney in reptiles, as in all amniote vertebrates, is retained as the functional kidney in adults.