part of overlaps expresses gcm larval tracheal system larva peritracheal cell embryonic/larval peritracheal cell fly_anatomy.ontology These three-cell clusters can be identified by expression of gcm (Laneve et al., 2013). Cell located at the branch points of the embryonic or larval trachea. It is part of a bilaterally-symmetrical, segmentally-repeated cluster of three cells that are connected by cytoplasmic processes (Laneve et al., 2013). These clusters are found in six abdominal segments, one to three thoracic segments and the head region (Laneve et al., 2013). One cell per cluster is a non-neuronal peptidergic cell (PM cell), which shows a complex morphology and extends several cytoplasmic processes. The PM cell is located on the main dorsal trunk trachea and the non-peptidergic cells (PMa cells) are located on the transverse tracheal connective (O'Brien and Taghert, 1998; Laneve et al., 2013). FBbt:00006017 embryonic/larval PT cell larval peritracheal cell