Further observations on the cetacean reniculus

SYNOPSIS The histological structure of the reniculus is described for the first time in the cetacean forms Delphinaptera leucas, Delphinus bairdi, Stenella styx, Stenella attenuata and Sousa plumbea . A sporta perimedullaris musculosa is shown to be present in all. A common pattern of renicular vascular arrangements is described and renicular venous return is shown to be effected by alternative renicular and perirenicular pathways. Such pathways constitute the sole radicles of the renal vein and no “wandering” veins emerge from the kidney surface.