A series of crescentic folds of mucous membrane somewhat spirally arranged on the interior of the gallbladder and continuing into the cystic duct. [ http://en.wikipedia.org/wiki/Spiral_valves_of_Heister http://dictionary.reference.com/browse/spiral+valve ]
Synonyms: plica spiralis Heister's valve plica spiralis (ductus cysticus) spiral fold of cystic duct valve of Heister