Renal vascular cast of the common tree shrew (Tupaia glis) as revealed by scanning electron microscopy

Abstract

The renal vascular casts of the common tree shrew were constructed by Batsons no. 17 plastic compound and viewed under SEM. Adult common tree shrew of both sexes weighing between 120 g to 180 g were used, Under ether anaesthesia, 0.05 ml of heparin was injected, the right atrium was cut opened, then 250-300 ml of 0.9% NaCl solution was perfused, both through the left ventricle. After hardening, the plastic mixture injected specimens were macerated in 40% KOH, washed in water and dried at room temperature. Then the plastic corrosion casts of the kidney were dissected free, studied under stereomicroscope, and coated with carbon and goldpalladium before viewing under SEM at 5-20 kV. It was found that each kidney received its blood supply from the renal artery that divided into interlobar arteries upon entering the kidney. The interlobar arteries radiated through the medulla and branched into arcuate arteries at the area representing corticomedullary junction. These arcuate arteries gave rise to interlobular arteries projecting toward the cortical area before giving off numerous afferent arterioles to form the glomerular capillary tuft from which efferent arterioles were derived. The renal vein and its tributaries were seen accompanying the renal artery and its branches which were demonstrated up to the interlobular vessels. The interlobular arteries occasionally gave off another type of branches which branched into capillary network without forming glomeruli called aglomerular arteriole. Furthermore, it was found that most of the blood vessels in the renal medulla were venules containing fenestrations on the surface. They arranged themselves in a parallel fashions running from corticomedullary area to the pyramidal region and there were numerous of fenestrations evenly distributed on the glomerular capillary wall.