part of tracheal lateral trunk posterior branch primordium LTp fly_anatomy.ontology Posteriorly directed ventral branch of the tracheal primordium that gives rise to the posterior portion of the lateral trunk in each tracheal metamere. It arises as the posterior side of a bifurcation at the ventral end of the tracheal primordium during stage 12. It fuses with posterior branch of the lateral trunk of the next segment to its posterior during stage 14 or 15. FBbt:00000244 tracheal branch primordium tracheal lateral trunk primordium primary segmental tracheal branch primordium