Answer:
Release ACh parasympathetic postganglionic fibers
Explanation:
In Autonomic nervous system fibres come from CNS to ganglion are the Preganglionic fibres .
The first neurotransmitter released by all the preganglionic nerve fibers either sympathetic or parasympathetic is acetylcholine (ach) and the first postganglionic receptor for all the nerve fibres is the nicotinic receptor (parasympathetic).
At the synapses within the ganglia , the preganglionic neurons release acetylcholine (ACh) which acts on the nicotinic acetylcholine receptors on the postganglionic neurons.
