Renal Vasculature of 2 Dasyurid Marsupials, Sminthopsis-Dolichura and S-Crassicaudata

Abstract

The renal vasculature of two dasyurid marsupials, Sminthopsis dolichura and S. crassicaudata, was examined using scanning electron microscopy of vascular corrosion casts of the kidney. Each species had a pair of unipapillary kidneys and the structural organisation of the major renal arterial vessels was similar to that of other placental mammals. The glomerulus of both species consisted of a network of dividing and anastomosing capillary loops. The glomeruli varied markedly in size, shape and complexity. Some afferent arterioles extended back towards the renal medulla, positioning the glomeruli closer to the cortico-medullary border. This placement of glomeruli may extend the loop of the nephron further into the medulla and thereby enhance counter-current water reabsorption and the final urine concentration. In both S. crassicaudata and S. dolichura, a dense mesh of numerous fine capillaries lined the wall of the renal pelvis adjacent to the inner medulla, with a unique configuration in that they were aligned perpendicular to the vasa recta. The function of these fine capillaries is unknown.