Kidney medulla blood vessels, light micrograph. Renal cortex of an albino rat perfused with a colloidal charcoal suspension to mark the renal blood vessels. At centre is an interlobular artery, from which branches directed towards the renal corpuscles (afferent arterioles) arise. After passing through the renal corpuscles, the efferent arterioles branch again between the convoluted tubules of the renal cortex. In this image the tendency of the outermost cortical peritubular network capillaries to go towards the renal surface where they will lead to the stellate veins is very evident.