circular fold

circular fold

one of the numerous annular projections in the small intestine. They vary in size and frequency in the duodenum, the jejunum, and the ileum and are formed by mucous and submucous tissue. Also called plica circularis, valve of Kerkring.
References in classic literature ?
At the sight of the deep, circular folds of skin on the forehead, the sodden, fish-like eyes, and the head, with its short, coarse, scantily-growing hair--a head utterly divested of all the faculties of the senses--who would not have experienced, as Genestas did, an instinctive feeling of repulsion for a being that had neither the physical beauty of an animal nor the mental endowments of man, who was possessed of neither instinct nor reason, and who had never heard nor spoken any kind of articulate speech?
Each circular fold is circularly arranged and extends about one half to two thirds of the way around the circumference of the lumen.
In the intestines of mammals and birds, the organization of luminal folds includes crypts within the circular folds that further increase surface area, but these crypts are not present in amphibian intestinal tracts.
Rectal prolapse will often have a target-like appearance with circular folds of tissue circumferentially protruding from the anus--often up to 10-15 cm.