part of open tracheal system development dorsal trunk growth, open tracheal system Growth of epithelial tubes that originate from pits in an open tracheal system and grow towards each other to meet and form a continuous open tube called the dorsal trunk. The dorsal trunk extends from the anterior spiracle to the posterior spiracle of the larva and forms the main airway of the insect tracheal system. dorsal trunk growth biological_process GO:0035001 developmental growth involved in morphogenesis