part of pupal tracheal system pupal tracheal section fly_anatomy.ontology pupal trachea The embryonic/larval dorsal branches posterior to tracheal metamere 5 collapse and are non-functional in the pupa - although may be maintained in a non-functional state as a template for growth of the adult system (Manning and Krasnow, 1993). Section of the pupal tracheal system. The basic framework (primary trachea) develop using the larval trachea of tracheal metameres 1-5 as a template (Whitten, 1957). But the new branches that develop from this basic framework are limited to the pupal and pharate adult stages have a distinct morphology. New pupal branches appear as many grape-like clusters of tracheoles lying free in the body cavity. Each cluster contains many fine tracheoles, with as many as 100 arising from a single point. Each tracheolar initially cell has a tightly coiled, snail-like tracheolar lumen that uncoils during the pupal period, extending towards and attaching to the developing pharate adult tissues. FBbt:00002956 tracheal section