The branches of renal artery at the hilus extend radialy between the pyramids as the inter lobar arteries. At the cortico-medullary junction they bend sharply and form short arches, the arcuate or arciform arteries.
The arcuate arteries give a number of interlobular arteries, which ascend vertically through the cortical labyrinth towards the surface. From these interlobular arteries small branches enter the glomeruli as the afferent vessel. The presence of JG cells in the afferent glomerular arteriole has been described with the structure (Renal Corpuscle).
The efferent glomerular arteriole after leaving the corpuscle divides into a system of capillaries – the peritubular plexus that form a dense network around the tubules of the cortex. The arterial supply to the medulla is furnished by efferent glomerular vessels of those renal corpuscles, which lie close, the medulla. These vessels, the arteriolae rectae spurlae pursue a straight course into the medulla and give rise to capillary nets, which extends to the apex of the pyramids.
The blood from the cortex is collected into small venules, which unite beneath the capsule to form stellate veins. From these arise interlobular veins, which receive small veins in the cortex and open into arcuate veins. Straight veins form the medulla open directly into arcuate veins. From the arcuate veins large interlobular veins pass between the medullary pyramids to form the renal vein.
