While chromaffin cells are closely related to post-ganglionic sympathetic neurons, they don’t actually form them. Instead, they act like post-ganglionic sympathetic neurons in function, but they’ve evolved to release hormones directly into the blood.
Chromaffin cells behave like post-ganglionic sympathetic neurons because they:
Are activated by pre-ganglionic sympathetic neurons via acetylcholine.
Release catecholamines (epinephrine and norepinephrine), which are the same neurotransmitters used by sympathetic neurons.
BUT:
Instead of releasing neurotransmitters at a synapse, chromaffin cells release hormones directly into the bloodstream.
That’s why they’re called neuroendocrine cells—they bridge the nervous and endocrine systems.
Chromaffin cells: Release epinephrine and norepinephrine into the bloodstream for body-wide effects.
Post-ganglionic sympathetic neurons: Release norepinephrine at target tissues (like the heart or blood vessels) for localized effects.