Scanning electron micrograph of the interior of an edible mushroom, Coprinus disseminatus, commonly called the crumble cap. The visible mushroom ("fruit body") appears only after the fungus grows for years in the soil. It produces millions of special cells called basidia from a surface layer known as the hymenium. In this micrograph, the basidia are the elliptical cells at top; at bottom is the hymenial layer in cross-section. Sexual union occurs in the basidia and results in formation of small cells, or basidiospores, which are released and dispersed by air currents to found new colonies of the fungus. Magnification: 680x at 35mm size.