[TA] parallel, tubular, epithelial pits (crypts) with openings at the bases of the intestinal villi; their thin walls are formed by columnar epithelial cells: mostly undifferentiated stem and intermediate cells and an increasing number of goblet cells as the small intestine proceeds distally, all of which migrate out of the glands onto the villi, but also protein- (enzyme-) secreting Paneth cells that remain in the glands.glands of large intestine. SYN: glandulae intestini tenuis [TA], crypts of Lieberkühn of small intestine.