part of tracheal dorsal trunk posterior branch primordium fly_anatomy.ontology Posteriorly directed dorsal branch of the tracheal primordium. Fuses to the anterior branch of the dorsal trunk of the tracheal primordium of the next segment posterior to it during stage 14. FBbt:00000223 DTp tracheal branch primordium tracheal dorsal trunk primordium primary segmental tracheal branch primordium