RIV is a pair of interneurons/motoneurons with cell bodies situated sub-dorsally in the lateral ganglia. Processes from each cell body enter the ring sub-dorsally, cross over to the contralateral side of the ring, and then run round it in the middle of the neuropile until they meet at the ventral mid-line in the anterior region of the neuropile of the ventral ganglion. At this point the processes turn round and run dorsally along the inside surface of the nerve ring, eventually ending laterally. Small projections at the region of contact run anteriorly and posteriorly from each process adjacent to the basal lamina on the inside of the ring. Darkly staining regions adjacent to the lamina are seen near the ends of these projections (b). The main synaptic outputs are to SAAD via fairly prominent monadic synapses (a, e) and NMJs (c, d). There are also smaller synapses to RMD (d), SMD (d), SIA (f) and RIA (e). All the synaptic outputs are in the ventral region of the nerve ring. The main synaptic inputs are from RIA (*b). Gap junctions are made to SDQ (a, e), SMD (g), AIB (h) and to itself (e). Magnifications: (a, b, d-h) x 25500, (c) x 17000.
Web adaptation, Thomas Boulin, for Wormatlas, 2001, 2002