SIB is a set of four interneurons, which send processes posteriorly down the sub-lateral cords. SIBV has cell bodies, in the ventral ganglion, which send processes that run right round the nerve ring and return to the neuropile of the ventral ganglion (f). They then enter the ventral sub-lateral cords via the amphidial commissures along with four other processes. The SIBD pair have cell bodies situated in the lateral ganglia. They send processes into the ventral cord via the amphidial commissures and then run round the nerve ring, leaving it sub-dorsally on the contralateral side along with the four other processes that make up the dorsal sub-lateral cords (e). No presynaptic contacts have been seen on these cells except for occasional regions that show typical presynaptic specializations but have no vesicles (a). In one place the process of an SIBD cell was seen in the motor endplate region of the nerve ring (b) but again no vesicles were seen. SIB has synaptic input from OLQ (*b) and has gap junctions to RIB (c), itself (SIBD to SIBV), AVB (d) (SIBV only) and AIM (*d) (SIBD only). SIB is similar in some respects to SIA and their two sets of processes run together in the nerve ring near the centre of the neuropile (SIA-d) . Magnifications: (a, d) x 25500, (b, c) x 12750.
Web adaptation, Thomas Boulin, for Wormatlas, 2001, 2002