Ultrastructure of acetylcholinesterase synthesizing neurons in the neostriatum.

Acetylcholinesterase (AChE) ultracytochemistry with thiocholine method was studied in the rat neostriatum. AChE synthesizing neurons were identified by observing reappearance of the enzyme after application of an AChE inhibitor, DFP. Neurons in the neostriatum were classified into 6 types. All such types were demonstrated to synthesize AChE. Two types of efferent neuron (types III and IV) have shown a relatively large amount of AChE and resynthesized the enzyme in the earlier stage after DFP. A tentative model of the neuronal network in the neostriatum was schematically shown.