Renal morphology of the hook‐lipped african rhinoceros, Diceros bicornis, linnaeus

Abstract

The kidney of Diceros bicornis has about 60 lobes, all appearing peripherally. These are separated by interlobar septa, except for small septal defects through which tubules pass. Renal capsule and interlobar septa are fibromuscular and contain small blood vessels. The kidney is about 65% cortex. It contains about 12.5 x 10(6) glomeruli, which form about 7% of the cortical mass and 4.6% of the renal mass. Diameter of a glomerular capsule is about 244 microns, there being no difference in size across the cortex in these adults. The ureter bifurcates into a cephalic and a caudal, fibromuscular, urothelial-lined conduit, into which open about 23 urothelial-lined infundibula. The common large collecting duct, or tubus maximus, of every lobe opens at the apex of its infundibulum. Two tubi may join into one infundibulum. The tubi and their terminal collecting ducts (of Bellini) are part of the inner medulla. Musculature of conduits and infundibula is largely longitudinal. The calyx may be represented by a circular muscle bundle near the apex of every infundibulum. The large intralobar veins are partly adherent to their infundibulum and calyx and receive arcuate veins via valved orifices. Most branches of the renal artery enter via the interlobar septa. Within a septum they branch again and also supply numerous perforators, which thence enter the cortex. Remaining branches of the renal artery enter cortex directly from without. A fibromuscular scaffolding lies deep to arcuate veins where they contact medulla. Where these veins contact cortical tubules; however, their walls become merely endothelium, like the walls of the interlobular veins.

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

“…The interlobar septa are fused tightly where no interlobar artery courses. This manner of arterial supply to the renal lobes is identical to that in two other species of rhinoceros, Rhinoceros unicornis and Ceratotherium simum (Maluf, 1989b(Maluf, , 1991a.…”

“…In the writer's experience this fraction is outstripped by the adult manatees (Maluf, 1989a). 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 The swamp-dwelling Asiatic rhinos, Rhinoceros unicornis (Maluf, 1987) and Dicerorhinw sumatrensis (unpublished observations), show medullae of 24.7 and 32.9% of renal mass, respectively.…”

“…29455 (Table 1) make it desirable to put this fact into perspective. Hence the graph of Figure 14 which represents data for the kidneys of adult mammals collected from Welcker and Brandt (1903), Spector (19561, and Maluf (1987,1989,1991aand unpublished findings). The small mammals, with higher metabolic rates per unit body mass (Benedict, 1938;Brody, 1945;Schmidt-Nielsen, 1983) have a higher renal mass relative to their body mass.…”

“…Counting of glomeruli has been described in detail (Maluf, 1989a(Maluf, , 1991a. Pieces of central cortex, checked by dissecting microscope to exclude possible residual medulla, were carefully mopped on absorbent paper and weighed to the nearest mg and then disintegrated at room temperature with 7.4 N (27%) HC1.…”

“…Relative renal mass of mammals is inversely proportional to their adult body mass. This is indicated by a regression line which includes rhinocer- uli, Renal collecting system After completion of the previous work on the kidney of Diceros bicornis (Maluf, 1991a), it became desirable to study the following: (1) Relations of the renal lobes to one another and to the pelvic conduits; (2) Status of the prominent longitudinally disposed veins which are closely related to the pelvic conduits; (3) Confirmation of passage of the interlobar arteries through the interlobar septa.The histologically normal kidneys of a healthy pregnant D. bicornis appeared exceptionally large, making it desirable to put them into perspective with sizes of the kidneys of other mammals including rhinoceroses. Additionally, her 75 mm fetus required description of the meso-and metanephros.…”