Acetylcholinesterase-immunoreactive axonal network in monkey visual cortex.

Immunocytochemistry with antibodies to human erythrocyte acetylcholinesterase (AChE) was used to demonstrate axons containing this enzyme in the visual cortex (area 17) of macaques. AChE-positive fibers were most dense in layers I, IIIB, IV, and VIB of Hassler and Wagner (I, IVA, IVC, and VIB of Brodmann) with three strata of more sparsely distributed fibers (layers II-IIIA, IIIC, and V-VIA of Hassler and Wagner [II-III, IVB, and V-VIA of Brodmann]). Layer I contained the most dense plexus of AChE-positive axons, oriented horizontally. Horizontally oriented axons were also located in layers IIIB, IIIC, IV, and V of Hassler and Wagner (IVA, IVB, IVC, and V of Brodmann). Layer VIB contained axons of variable orientation, apparently afferent to cortex. Moderately stained neuronal perikarya were occasionally encountered in layer VIB and superficial white matter, but no intensely stained neurons were seen.