Zebrafish muscle. Confocal light micrograph of the interior of an intact zebrafish (Danio rerio) larva. The tissues have been stained with fluorescent dyes and illuminated with a laser: cell nuclei appear yellow. The long, dark, striated objects are individual muscle cells. A confocal microscope detects light only from the focal point of its objective lens. By moving the focal point, sharp images of thin sections of an intact specimen can be obtained. Magnification: x200 at 6x6cm size.