AIN is a set of two interneurons with cell bodies situated in the lateral ganglia. Processes project anteriorly and enter the nerve ring sub-dorsally. They run round the ring to the contralateral side on the outside surface and then enter the ventral cord, eventually petering out in the region of the ventral ganglion. The main synaptic output is to AFD (a, d), BAG (b), RIB (c), and ASE (a). The cephalic sheath cells may also be receiving synaptic input from AIN at dyadic synapses (b). AIN has no significant synaptic inputs but has gap junctions with ASG, AUA (*d) and itself. Magnifications: (a) x 25500, (b-d) x 12750.