in taxon Vertebrata <vertebrates> embryonic structure post-anal tail bud UBERON:0002533 EHDAA2:0001976 end bud tailbud Rapidly proliferating mass of cells at the caudal extremity of the embryo. Its formation is reflected in a caudal carving of the posterior portion of the archenteric canal at NF stage 22. With its further outgrowth, the postanal gut primordium becomes stretched. Its lumen is in broad communication with the hindgut at NF stage 25.[AAO] EHDAA:1595 TAO:0000077 AAO:0011104 The rapidly proliferating mass of cells at the caudal extremity of the embryo; remnant of the primitive node. VHOG:0000201 ZFA:0000077 XAO:0000107 EMAPA:16580 uberon MIAA:0000070 MAT:0000070 tail bud BTO:0001445 tail bud mesenchyme (...) at some stage of its development, every chordate exhibits five uniquely derived characters or synapomorphies of the group: (...) (5) a larva or embryo with a postanal tail.[well established][VHOG] EFO:0002748 See notes from https://github.com/obophenotype/uberon/wiki/The-neural-crest