RIH is an interneuron with a single, large, cell body situated on the ventral mid-line at the anterior end of the ventral ganglion (figure 16). A process comes off the cell body posteriorly and then turns and runs ventrally to the ventral extremity of the neuropile. It then runs anteriorly in this position until it bifurcates with each process running round the outside surface of the nerve ring. These two processes appear symmetrical; however, the left-hand one ends after a short distance and the right-hand process changes direction and runs anteriorly through the neuropile of the nerve ring until it reaches the anterior surface. At this point the process bifurcates again and each branch runs round the ring and ends near the dorsal mid-line. The unusual architecture of this neuron results in its processes' inhabiting two quite separate neighbourhoods. The main synaptic outputs after the first bifurcation are to RIA (a), AIZ (a) and RIB (b) at dyadic synapses. After the second bifurcation, the main synaptic outputs are to RIP (c), OLQ (c), at dyadic synapses, and CEP. The main synaptic input is from IL2 (*c, *d). RIH has gap junctions with ADF (d), CEP, OLQ (*g) and FLP (*d). Magnifications; (a) x 25500, (b-d) x 17000.
Web adaptation, Thomas Boulin, for Wormatlas, 2001, 2002