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Light and electron microscopic analyses of intraspinal axon collaterals of sympathetic preganglionic neurons.

Abstract：

:Experiments were performed in pigeons (Columba livia). Sympathetic preganglionic neurons (SPNs) in the first thoracic spinal cord segment (T1) were identified electrophysiologically using antidromic activation and collision techniques and then intracellularly labeled with horseradish peroxidase (HRP). In 6 of 10 HRP-labeled SPNs, the site of axon origin and intraspinal axonal trajectory could be specified. In 2 of the 6 HRP-labeled axons, the peripherally projecting process branched intraspinally. The presence or absence of SPN intraspinal axonal collateralization did not correlate with parent perikaryal subnuclear location or dendritic alignment. None of the collaterals were recurrent onto the SPN of origin. Light microscopically, the collateral branches appeared to end with punctate, bulbous swellings. The spinal regions of the terminal end swellings for the two axons did not overlap one another. In one instance the entire terminal field was confined within the principal preganglionic cell column (column of Terni). The other axon had collateral branches which terminated in the lateral white matter and in a ventrolateral region of lamina VII. A serial section, electron microscopic reconstructive analysis of the entire intraspinal collateral terminal field within the column of Terni revealed that: (a) the primary collateral process was unmyelinated and arose at a node of Ranvier; (b) after issuance of the collateral branch, the myelinated parent axon continued to increase its myelin wrapping throughout the spinal gray; (c) the bulbous swellings observed light microscopically corresponded to axon terminal boutons and regions of synaptic contact; (d) the axon collateral terminals were exclusively presynaptic to small caliber dendrites and formed only asymmetric specializations; and (e) the collateral terminals contained numerous mitochondria, and densely packed, electron-lucent, spherical vesicles.

journal_name

Brain Res

journal_title

Brain research

authors

Bogan N,Cabot JB

doi

10.1016/0006-8993(91)91024-u

subject

Has Abstract

pub_date

1991-02-15 00:00:00

pages

241-51

issue

eissn

0006-8993

issn

1872-6240

pii

0006-8993(91)91024-U

journal_volume

541

pub_type

杂志文章

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Light and electron microscopic analyses of intraspinal axon collaterals of sympathetic preganglionic neurons.