Abstract
Abstract: :
Purpose: While an Edinger-Westphal nucleus (EW) has been designated in the human midbrain, based on cytoarchitectonic grounds, the actual location of the preganglionic parasympathetic motoneurons supplying the ciliary ganglion within this complex region has not been determined in man. We attempted to identify a set of markers for the preganglionic motoneurons of the EW in the macaque monkey that might be utilized as tools to positively identify this population in human brains. Methods: Wheatgerm agglutinin (WGA) was injected into the ciliary ganglion of macaque monkeys to retrogradely label preganglionic motoneurons in the EW. Adjacent sections were reacted using antibodies to: WGA, choline acetyl transferase (ChAT) and calcium binding proteins; or reacted histochemically to reveal the presence of cytochrome oxidase or NADPH diaphorase. Results: The WGA labeled preganglionic motoneurons formed a single compact column of cells located almost immediately dorsal to the oculomotor nucleus. This column extended from the caudal central subdivision to just rostral of the oculomotor nucleus, ending within the anteromedian nucleus. ChAT antibody labeled the large, somatic oculomotor neurons, and the small, slow-twitch (C-group, etc.) motoneurons located immediately dorsal and medial to the somatic motoneurons. In addition, anti-ChAT labeled large neurons in the same position as the preganglionic motoneurons labeled with WGA. Anti-calretinin lightly labeled somatic motoneurons, but heavily labeled interneurons in the supraoculomotor area (SOA). Anti-parvalbumin darkly labeled large, somatic motoneurons, but did not label small, slow-twitch (C-group, etc.) motoneurons or EW motoneurons. Cytochrome oxidase positive cells were prominent in both the oculomotor nucleus and in EW, but slow-twitch and SOA interneurons were cytochrome oxidase negative. NADPH diaphorase positive cells were only found within the distribution of the slow-twitch motoneurons. Conclusion: EW preganglionic motoneurons in the macaque form a single cell column, in contradistinction to previous reports of the subdivision of EW into multiple columns. These preganglionic EW motoneurons are ChAT and cytochrome oxidase positive, but parvalbumin, calretinin and NADPH diaphorase negative. This pattern of characteristics should allow EW preganglionic motoneurons to be distinguished from neighboring cell populations in human brain sections. The differences in calcium binding proteins may underlie the specificity of Alzheimer's neurotoxicity in this area.
Keywords: 304 accommodation • 495 ocular motor control • 534 pupil