Final answer:
The cell bodies of parasympathetic preganglionic nuclei are located in the brainstem and sacral spinal cord. These nuclei project to terminal ganglia to release ACh and stimulate 'rest-and-digest' responses.
Step-by-step explanation:
The cell bodies of parasympathetic preganglionic nuclei can be found in two primary locations: the brainstem and the sacral spinal cord. Specific nuclei within the brainstem include the dorsal nucleus of the vagus nerve and the Edinger-Westphal nucleus. The preganglionic neurons in these locations project to terminal ganglia located near or within the walls of target organs, where they release acetylcholine (ACh) onto nicotinic receptors to excite the ganglionic neurons. Following this excitation, postganglionic fibers release ACh onto muscarinic receptors to elicit the 'rest-and-digest' responses characteristic of the parasympathetic nervous system.
Therefore, the correct answer to the question is: a. Brainstem and sacral spinal cord. The thoracic and lumbar spinal cord are associated with the sympathetic division of the autonomic nervous system, not the parasympathetic system. Additionally, the cervical spinal cord is not typically associated with parasympathetic outflow.