Embryonic motor neuron precursor that develops from the first ganglion mother cell in the 7-3 lineage (GMC 7-3a) (Higashijima et al., 1996; Isshiki et al., 2001) and is the Notch ON descendent of this GMC (Lee and Lundell, 2007). One of these cells is produced in each thoracic, abdominal (A1-A8) and labial hemisegment (Higashijima et al., 1996; Rogulja-Ortmann et al., 2007; Rickert et al., 2018). It only develops into a larval neuron in segments S3-T2, in more posterior segments it undergoes programmed cell death (Rogulja-Ortmann et al., 2007; Rickert et al., 2018).
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).
Serotonergic interneuron of embryonic/larval abdominal segments A1-A7. Its contralateral branch forms a complex pattern at the ventral border of the contralateral neuropil that extends along the lateral margins. Its ipsilateral branch seems to fasciculate with the respective neurite of the serotonergic abdominal medial neuron and follows a similar pathway, though extending a contralateral neurite about mid-level in the dorso-ventral and anterior-posterior axis. This neurite extends a short way anterior along a midline tract. It is born from the second-born ganglion mother cell of the 7-3 lineage (GMC 7-3b).
Larval corozonergic interneuron that develops from the third GMC in the NB7-3 lineage (GMC 7-3c) (Novotny et al., 2002). There is one of these cells per hemisegment from T2 to A7 (Novotny et al., 2002).
Larval interneuron that is derived from neuroblast NB7-3. These are the Notch OFF cells born from the three GMCs produced by NB7-3 (Lee and Lundell, 2007). They are all primary neurons, since NB7-3 does not generate a secondary lineage (Lacin and Truman, 2016). There are usually three of these per hemineuromere from S2-A8, but only two are found in each mandibular (S1) hemineuromere (Rickert et al., 2018). They project contralaterally (Higashijima et al., 1996; Rickert et al., 2018).