Sun Wensi, May Paul J
Department of Neurobiology and Anatomical Sciences, University of Mississippi Medical Center, Jackson, Mississippi, 39216.
J Comp Neurol. 2014 Dec 15;522(18):3978-4002. doi: 10.1002/cne.23601. Epub 2014 May 7.
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.
支配睫状神经节的节前运动神经元控制晶状体调节和瞳孔直径。在猫中，这些运动神经元构成节前动眼神经副核群，位于动眼神经核的嘴侧、背侧和腹侧。最近一项针对猫的研究表明，尾侧运动神经元控制晶状体，嘴侧运动神经元控制瞳孔。这促使我们研究这些神经元群的形态、超微结构和顶盖前输入。通过将示踪剂注入猫的睫状神经节而逆行标记的节前运动神经元通常分为两种形态类型。梭形神经元位于嘴侧，在前正中核以及动眼神经核之间。多极神经元位于尾侧，在动眼神经核的背侧和腹侧。前正中核内节前运动神经元的树突穿过中线，为同感性反应提供了可能的基础。在超微结构上，几种不同类型的突触形态与节前运动神经元相接触，这表明它们的活动可能受到多种输入的调节。此外，与嘴侧神经元群和尾侧神经元群相接触的突触群体存在差异，支持了这些神经元群具有功能差异的观点。观察到顺行标记的顶盖前终末与标记的节前运动神经元紧密相连，尤其是在嘴侧神经元群中。超微结构分析显示，这些终末充满了清亮的球形囊泡，与嘴侧神经元群中的运动神经元形成不对称突触联系，表明这些细胞参与瞳孔对光反射。因此，在猫中发现的节前运动神经元表现出形态、超微结构和连接上的差异，这表明嘴侧节前神经元群专门用于控制瞳孔，而更靠尾侧的部分则控制晶状体。
