Kidney stone

Density-dependent colour scanning electron micrograph of the surface of a histological slide from a kidney stone (nephrolithiasis). Kidney stones form when salts, minerals and chemicals in the urine (for example calcium, oxalate and uric acid) crystallise and solidify. The blue colour identifies denser material (calcified material composed of calcium phosphate), while structures that appear in green and red are less dense (corresponding to the organic component of the tissue). Micrographs were coloured in post-processing by combining images acquired by three modes of image acquisition that use different kinds of electron microscope detectors. Horizontal width of image is 33 microns.