somatic precursor cell bridge cell A mesodermal cell that is located in the posterior-lateral margin of a tracheal metamere from early in embryonic stage 12, adjacent to the just-forming dorsal trunk posterior branch (FBbt:00000223). During late stage 12 and stage 13, it forms a bridge between the dorsal trunk posterior branch (FBbt:00000223) of one tracheal metamere and the anterior branch (FBbt:00000213) of the adjacent (posterior) metamere. Following fusion during stage 14, this cell becomes displaced from the trachea. FBbt:00007587 fly_anatomy.ontology tracheal fusion bridge cell trunk mesoderm derivative