directly develops from larval EW neuron EW1 neuron Serotonergic interneuron of embryonic/larval abdominal segments A1-A7. The axon bifurcates into two thick branches as it enters dorsally into the contralateral neuropil. These two primary branches initially diverge in opposite directions and grow along the medial two-thirds of the neuropil, forming a circular pattern, with the branches meeting at the dorsal end of the neuropil. These neurons also extend an ipsilateral neurite, that seems to fasciculate with the respective neurite of the serotonergic abdominal lateral neuron and follow a similar pathway, projecting anteriorly to form the majority of its branches in the next anterior segment. In the A7 abdominal segment, this neuron has a single primary neurite that extends centrally and forms extensive varicosities. It is born from the first-born ganglion mother cell of the 7-3 lineage (GMC 7-3a). larval serotonergic abdominal medial neuron fly_anatomy.ontology FBbt:00001583 VFB:FBbt_00001583 ganglion mother cell GMC7-3a larval serotonergic abdominal neuron