Scanning electron micrograph of two macrophage cells four hours after infection with Candida yeast spores. The projections seen here extending from the macrophages are candida hyphae growing within the cell. This will eventually kill the cells by causing them to burst. Macrophages are white blood cells of the immune system which engulf and destroy foreign material. They are found in all tissues of the body. Overgrowth of yeasts can result in fungal infections such as thrush (candidiasis). Horizontal image width is 65 microns. Supplied by Kevin Mackenzie, courtesy of Wellcome Images.