RIG is a set of two interneurons with cell bodies situated in the retro-vesicular ganglion.
Processes from each cell body run anteriorly, closely apposed in the middle of the ventral cord.
As they approach the nerve ring, the processes move down into the ventral region of the nerve
cord. They then enter the nerve ring and run round each side of it, near the anterior face and
outside surface of the neuropile, until they meet and terminate on the dorsal mid-line with a
gap junction. The main synaptic output is to RIR (a), RMH (b), AVE (c), AIZ (c), AVK (b), RIB (d) and BAG (d). There are extensive synaptic inputs from ADE (*a) in the neuropile
of the ventral ganglion and some synapses from DVC (*a), PVP (*b), URX (*d), BAG (*b)
and DVB in the nerve ring. RIG is striking because of the quantity and diversity of its gap
junctions. It has gap junctions with itself (e), URY (c, h), OLQ (*f), OLL (f), RIB (g), BAG (h), AQR and AVK.
Magnifications; (a, h) x 25500, (b-d, f) x 17000, (e, g) x 12750.
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