Kidney of the sumatran rhinoceros, Dicerorhinus sumatrensis

The kidney of Diceros sumatrensis has the rhinocerotic form and lobation. The ureter divides intrarenally into two fibromuscular conduits which receive, at separate loci, the terminal collecting ducts of the lobes. The kidney is 67% cortex. Total renal mass is 0.46% of body mass. There are about 34 lobes and 23 primary orifices at the conduits. Glomeruli are relatively small and of the same size across the cortex. They number about 14.6 million in one kidney but the glomerular mass is relatively low. Unlike other rhinocerotic species, the kidney of D. sumatrensis lacks interlobar septa. The interlobar arteries nevertheless enter the renal parenchymas as in the other rhinoceroses, i.e., between the cortices of adjacent lobes rather than in the common mammalian manner between cortex and medulla. Thus, internal “perforator” arteries pass from cortical periphery to interior giving off cortical twigs on their way to the corticomedullary border, along which they branch while releasing centrifugal arteries back toward the cortical periphery. The arcuate veins are wide centrally where they enter the paraconduital veins. The latter form prominent central anastomoses between the large interlobar veins. © 1993 Wiley‐Liss, Inc.