Light micrograph of a section through the medulla (left and centre) and cortex (right) of a kidney. The cortex of the kidney consists mainly of blood vessels and filtering units (round). The filtering units are made up of a glomerulus (purple) and a Bowman's capsule (white). The core of each glomerulus is formed of a tightly coiled capillary. Its function is to filter waste products from the blood. Fluid drains through the proximal convoluted tubules (pink tubes, surrounding glomerulus) and loops of Henle in the medulla (purple tubes) into collecting ducts that transport it to the bladder as urine. Magnification: x40 when printed at 15cm wide.