Acetylcholinesterase-containing neurons in cat neostriatum: a morphological and quantitative analysis.

When examined in brain sections prepared according to the Butcher's pharmaco-histochemical method, the large acetylcholinesterase (AChE)-containing cells in cat putamen appear morphologically different, more numerous per mm2, and significantly larger than those in caudate nucleus. Such a finding supports the view that the feline neostriatum is not a homogeneous structure. In addition, horseradish peroxidase (HRP) injected into the various target nuclei of neostriatum labels numerous medium-sized striatal cells and a few large-sized putaminal neurons. However, no HRP material could be detected in the large AChE cells themselves, suggesting that these cells are not output neurons.