Light micrograph showing glomeruli (the dark features) in a human kidney affected by chronic glomerulonephritis. This type of kidney disease most commonly occurs in children and often follows a streptococcal bacterial infection, usually of the throat. The condition is marked by a proliferation of the endothelial cells lining the glomerular capillaries and the presence of increased numbers of neutrophils. Obstruction of the glomerular capillaries causes red blood cells to leak into the urine (haematuria). Fluid retention & swelling (oedema) are other symptoms. Magnification: x20 at 35mm size.