Locus ceruleus somata contain both acetylcholin esterase and norepinephrine: direct histochemical demonstration on the same tissue section.

In the same brain section stained first for catecholamines and then for acetylcholinesterase (EC 3.1.1.7), it was found that neuronal somata in locus ceruleus containing norepinephrine also contained the cholinergic degradative enzyme. Cell body shapes were fusiform, pyramidal, round, or oval. Maximum soma extent ranged from 10--40 micrometers, with the proportion of large diameter neurons increasing, and the smaller diameter cells decreasing, from rostral to caudal cerulear levels. Medium-sized neurons were roughly constant throughout the nucleus. Acetylcholinesterase may be associated with cerulear somata and proximal processes containing norepinephrine to inactivate a cholinergic input to that structure.