Caption

Glomerulus. Coloured scanning electron micrograph (SEM) of a glomerulus in a human kidney. A glomerulus (centre) is a tight ball of capillaries where blood passing through the kidneys is filtered. Some red blood cells (erythrocytes) can be seen at lower left (mauve). Fluid passes out of the capillaries into the cavity of the surrounding Bowman's capsule (not clearly seen) and drains into a long tube (right), from which essential substances and some water are reabsorbed. The remaining unwanted fluid, containing toxins from the blood, drains to the bladder as urine. Magnification: x770 at 6x7cm size.