One of the simple tubular glands present in the intestinal mucosa. In the small intestine the crypts open between the bases of the villi, and their epithelium includes absorptive cells that produce digestive enzymes, enteroendocrine cells that secrete hormones, goblet cells that produce mucus, and Paneth cells that secrete lysozyme. In the large intestine the crypts open to the mucosal surface and secrete mucus.