Scanning electron micrograph (SEM) of a kidney glomerulus (podocytes and capillaries of the renal corpuscle). The glomerulus consists of a tightly coiled network of capillaries surrounded by podocytes. There about 1 million glomeruli in each kidney. Podocytes have narrow cell extensions (processes) that in turn give rise to secondary extensions called pedicels. The podocytes completely surround the capillary system. As blood passes through each glomerulus, water and metabolic wastes are filtered through capillary walls by the surrounding podocytes. About 100 litres of blood are filtered every hour. The water and waste pass into the lumen of the Bowman's capsule. From the capsule the water and waste drains into the surrounding tubules where reabsorption occurs. Magnification: x2,600 when shortest axis printed at 25 millimetres.