RIR is an interneuron with a single cell body in the ventral ganglion. An anteriorly directed process leaves the cell body and runs on the dorsal surface of the nerve cord on the mid-line. As the nerve ring is approached this process abruptly turns and moves down to the ventral surface of the nerve cord. At this point, it divides into two processes (b), which run round the nerve ring near the middle of the neuropile and terminate near the dorsal mid-line (d). The main synaptic outputs of RIR are to RIA (a), AIZ (c) and URX (a). The main synaptic inputs are from AVH (*a), RIG (*a), ADF and DVA (*e). There are gap junctions to BAG (*d). Magnifications: (a) x 25500, (b, d) x 12750, (c) x 17000.
Web adaptation, Thomas Boulin, for Wormatlas, 2001, 2002