Confocal image of colonic crypts in cross section. Mucin cells (yellow) in the crypts produce mucous which passes into the interior of the colon through the crypt lumen (the white spots in the centres of the crypts) to facilitate the movement of the faecal mass through the colon. Staining for F-actin (blue) shows the pericryptal sheaths. This tissue is from an endoscopic colonic biopsy for a child and shows the normal appearence of the colonic crypts.