del-1 is expressed in the VB motor neurons beginning in the L2 larval stage. By the end of L2,
del-1::GFP is also visible in a few VA motor neurons at the anterior end of the nerve cord. Expression of
del-1::GFP in the VAs progresses in a wave from anterior to posterior, with all VAs expressing
del-1::GFP by the adult stage. Thus,
del-1::GFP is not expressed in the VAs during the L2 period in which
unc-4 functions in these cells to establish synaptic inputs but is expressed in the VAs after they have been wired into the ventral cord circuit.
del-1::GFP is also expressed in five neurons (VB1, VB2, SABVR, SABVL, VA1) in the retrovesicular ganglion at the anterior end of the ventral nerve cord. During the mid-L2 larval stage,
del-1::GFP expression in the ventral nerve cord is largely restricted to the VB class of motor neurons.