A fetal membrane developing from the hindgut (or yolk sac, in humans). In humans it becomes a fibrous cord, the urachus; externally, in other mammals, it contributes to the formation of the umbilical cord and placenta; in birds and reptiles, it lies close beneath the porous shell and serves as an organ of respiration.
Synonym(s): allantoid membrane
[allanto- + G. eidos, appearance]
Search Stedman's Medical Dictionary
Examples: glitazone, GI cocktail, etc.