Kidney glomeruli. Coloured scanning electron micrograph (SEM) of two glomeruli (red) surrounded by supporting tissue (brown) in a kidney. The outer layer of these round structures are podocyte cells that interlock to cover an inner coiled ball of capillaries. The action of the blood flowing through this coiled ball filters toxins from the blood. Each kidney has hundreds of glomeruli that filter blood. The resulting waste fluid drains to the bladder as urine.