Macroanatomy of the renicule of the bowhead whale (Balaena mysticetus).

The macroanatomy of renicules and surrounding tissues from the kidneys of five Eskimo-harvested bowhead whales, Balaena mysticetus , was examined. These renicules are similar in overall structure to those of other cetaceans and intermediate in size. There are several important differences including the presence of arcuate vessels within the sporta perimedullaris , the extension of connective tissue from the sporta deep into the peripheral cortex, and the presence of very large, thin-walled veins that occupy the interrenicular spaces. Arterial and venous plexuses outside the substance of the sporta reported in other cetaceans were not observed in the bowhead .