Central pupillary light reflex circuits in the cat: II. Morphology, ultrastructure, and inputs of preganglionic motoneurons
Version of Record online: 7 MAY 2014
© 2014 Wiley Periodicals, Inc.
Journal of Comparative Neurology
Volume 522, Issue 18, pages 3978–4002, 15 December 2014
How to Cite
Sun, W. and May, P. J. (2014), Central pupillary light reflex circuits in the cat: II. Morphology, ultrastructure, and inputs of preganglionic motoneurons. J. Comp. Neurol., 522: 3978–4002. doi: 10.1002/cne.23601
- Issue online: 15 OCT 2014
- Version of Record online: 7 MAY 2014
- Accepted manuscript online: 5 APR 2014 03:57AM EST
- Manuscript Accepted: 3 APR 2014
- Manuscript Revised: 8 MAR 2014
- Manuscript Received: 9 JAN 2014
- National Eye Institute. Grant Numbers: EY07166, EY014263
- ciliary ganglion;
Preganglionic motoneurons supplying the ciliary ganglion control lens accommodation and pupil diameter. In cats, these motoneurons make up the preganglionic Edinger-Westphal population, which lies rostral, dorsal, and ventral to the oculomotor nucleus. A recent cat study suggested that caudal motoneurons control the lens and rostral motoneurons control the pupil. This led us to examine the morphology, ultrastructure, and pretectal inputs of these populations. Preganglionic motoneurons retrogradely labeled by introducing tracer into the cat ciliary ganglion generally fell into two morphologic categories. Fusiform neurons were located rostrally, in the anteromedian nucleus and between the oculomotor nuclei. Multipolar neurons were found caudally, dorsal and ventral to the oculomotor nucleus. The dendrites of preganglionic motoneurons within the anteromedian nucleus crossed the midline, providing a possible basis for consensual responses. Ultrastructurally, several different classes of synaptic profiles contact preganglionic motoneurons, suggesting that their activity may be modified by a variety of inputs. Furthermore, there were differences in the synaptic populations contacting the rostral vs. caudal populations, supporting the contention that these populations display functional differences. Anterogradely labeled pretectal terminals were observed in close association with labeled preganglionic motoneurons, particularly in the rostral population. Ultrastructural analysis revealed that these terminals, packed with clear, spherical vesicles, made asymmetric synaptic contacts onto motoneurons in the rostral population, indicating that these cells serve the pupillary light reflex. Thus, the preganglionic motoneurons found in the cat display morphologic, ultrastructural, and connectional differences suggesting that this rostral preganglionic population is specialized for pupil control, whereas more caudal elements control the lens. J. Comp. Neurol. 522:3978–4002, 2014. © 2014 Wiley Periodicals, Inc.