FURTHER-STUDIES ON THE KIDNEY OF THE HOOK-LIPPED AFRICAN RHINOCEROS, DICEROS-BICORNIS

A healthy, pregnant Diceros bicornis (No. 29455), with histologically normal but relatively large kidneys containing a correspondingly large number of nephrons, died suddenly from an injury. Renal lobation was studied partly from serial transverse cuts across the kidney. The fibr omuscular pelvic conduits, which are a craniocaudal bifurcation of the ureter, are associated with prominent longitudinally disposed paracon duital veins which anastomose with the interlobar veins. The arcuate v eins open widely into the paraconduital veins. The latter drain into t he major tributaries of the renal vein at the renal sinus. The interlo bar arteries enter the parenchyma through the interlobar septa. These arteries release internal perforator branches, through the septa, whic h pass to the corticomedullary border, branch along that border as arc uate arteries, and release cortical branches centrifugally. All these branches give off twigs to the glomeruli. Relative renal mass of mamma ls is inversely proportional to their adult body mass. This is indicat ed by a regression line which includes rhinoceroses. D. bicornis No. 2 9455, accordingly, has exceptionally large kidneys. The mesonephros of the 75 mm fetus of D. bicornis has mature glomeruli and tubules. The metanephros has pelvic conduits, paraconduital veins, but, as yet, no medullary loops. (C) 1994 Wiley-Liss, Inc.