Kidney of the great indian rhino Rhinoceros unicornis, linnaeus

Abstract

The kidney of R. unicornis has almost 80 closely apposed lobes, all appearing peripherally. Every lobe, almost enclosed by a collagenous septum, resembles a deformed truncated cone. The pelvis proper is a small pouch which divides into a cephalic and a caudal urothelial-lined fibromuscular conduit. The terminal collecting ducts of every lobe open into a tubus maximus. This is lined by cuboidal cells and otherwise has no wall. There is no papilla. All lobes finally empty through the 18 primary infundibular orifices at the pelvic conduits. A primary fibromuscular infundibulum typically yields a secondary one supplying an adjacent lobe. Two or three lobes can use a common tubus maximus by "convergence" of their medullae. Tubus maximus, terminal collecting ducts and deep outer medulla are embraced by a fibromuscular calyx which is the peripheral extension of an infundibulum and is fused to the outer medulla. There is thus no vault between medulla and calyx. Large intralobar veins are fused to the outer wall of the calyx. The possible significance of this is discussed. The cortex is the only part of a lobe which has contact with infundibulum, pelvic conduits, or pelvis proper. The kidney has about 16 million glomeruli which form 5.8% of the adult's cortical mass. Many adult mammals, from mouse to rhinoceros, fit into the log10-log10 slope relating number of glomeruli per kidney to body-mass. Neonatal rhinos at term have mature glomeruli throughout the cortex. The small size of the glomeruli and the large number per field allow 16 million in an 118-gm kidney.

Kidney of elephants

“…These papillae can be associated with a tubus maximus, which is "a supreme collecting duct lined by collecting duct epithelium, with no definitive wall and into which terminal collecting ducts open around. Thus the term is applicable to the cephalic and caudal extensions of the diminutive renal pelvis of the Equidae and Hippopotamidae, to the lobar branches of these extensions in the Hippopotamidae (Maluf, 1978(Maluf, , 1994b, and to the re-ceptacles of the terminal collecting ducts in every lobe of the Rhinocerotidae" (Maluf, 1987(Maluf, , 1989c(Maluf, , 1991a.…”

“…Renal mass per area cribrosa of adult elephants may exceed 285 g. This implies that every medullary outlet drains a large mass of kidney. Renal mass per lobe in adults of five species of rhinoceros is much less than in elephants, namely, 50 t 14g (data from Maluf, 1987Maluf, , 1991aMaluf, , 1994a. In man with a standard of 14 lobes per 150 g kidney, the mass per lobe is only 10.7 g.…”

“…The thin wall of these veins is actually fused in part to the calyces (Fig. 22 [V and CAI) as in the rhinocerotic kidney (Maluf, 1987) for which it was pointed out that an "analogy exists with the reciprocal relationship between pneumatic and venous sinuses at the base of the cetacean skull shown by Fraser andPurves (1954, 1960). "…”

Further studies on the kidney of the hook‐lipped African rhinoceros, Diceros bicornis

“…This, in part, results in disparity between number of lobes (51) and primary ostia (24). Such disparity occurs in the other species of rhinoceros, especially in Rhinoceros unicornis which has a greater number of lobes (Maluf, 1987;and unpublished findings).…”

“…In the two other adult Diceros bicornis females the medulla averaged 34.9% of the parenchymal mass (Maluf, 1991a). The swamp-dwelling Asiatic rhinos, Rhinoceros unicornis (Maluf, 1987) and Dicerorhinw sumatrensis (unpublished observations), show medullae of 24.7 and 32.9% of renal mass, respectively.…”