the Schwann cells provide insulation to axons in the Peripheral Nervous System while oligodendrocytes are of the Central Nervous System. So you'll pretty much find Schwann cells anywhere other than your brain and spinal cord. anyone please correct me if I'm wrong, it's been a while since i've taken the DAT haha
actually... the post-ganglionic neurons of the autonomic nervous system are NOT myelinated, but the pre-ganglionic neurons are. also know that acetylcholine is the NT between the two. however, the post-ganglionic ns will secrete either nori/epi for sympathetic ns and acetylcholine on the effector.