end bud [AS, ende + Gk, bolbos, onion] , a mass of undifferentiated cells produced from the remnants of the primitive node and the primitive streak at the caudal end of the developing embryo after formation of the somites is completed. In lower animals it gives rise to the tail or any other caudal appendage and part of the trunk. In humans it forms the caudal portion of the trunk. Also called tail bud.
