A role for cingulate pioneering axons in the development of the corpus callosum

Rash, B. G. and Richards, L. J. (2001) A role for cingulate pioneering axons in the development of the corpus callosum. Journal of Comparative Neurology, 434 2: 147-157.


Author Rash, B. G.
Richards, L. J.
Title A role for cingulate pioneering axons in the development of the corpus callosum
Journal name Journal of Comparative Neurology   Check publisher's open access policy
ISSN 0021-9967
Publication date 2001
Sub-type Article (original research)
DOI 10.1002/cne.1170
Volume 434
Issue 2
Start page 147
End page 157
Total pages 11
Place of publication New York
Publisher Wiley-liss
Language eng
Abstract In many vertebrate and invertebrate systems, pioneering axons play a crucial role in establishing large axon tracts. Previous studies have addressed whether the first axons to cross the midline to from the corpus callosum arise from neurons in either the cingulate cortex (Koester and O'Leary [1994] J. Neurosci. 11:6608-6620) or the rostrolateral neocortex (Ozaki and Wahlsten [1998] J. Comp. Neurol. 400:197-206). However, these studies have not provided a consensus on which populations pioneer the corpus callosum. We have found that neurons within the cingulate cortex project axons that cross the midline and enter the contralateral hemisphere at E15.5. By using different carbocyanine dyes injected into either the cingulate cortex or the neocortex of the same brain, we found that cingulate axons crossed the midline before neocortical axons and projected into the contralateral cortex. Furthermore, the first neocortical axons to reach the midline crossed within the tract formed by these cingulate callosal axons, and appeared to fasciculate with them as they crossed the midline. These data indicate that axons from the cingulate cortex might pioneer a pathway for later arriving neocortical axons that form the corpus callosum. We also found that a small number of cingulate axons project to the septum as well as to the ipsilateral hippocampus via the fornix. In addition, we found that neurons in the cingulate cortex projected laterally to the rostrolateral neocortex at least 1 day before the neocortical axons reach the midline. Because the rostrolateral neocortex is the first neocortical region to develop, it sends the first neocortical axons to the midline to form the corpus callosum. We postulate that, together, both laterally and medially projecting cingulate axons may pioneer a path for the medially directed neocortical axons, thus helping to guide these axons toward and across the midline during the formation of the corpus callosum. (C) 2001 Wiley-Liss, Inc.
Keyword Neurosciences
Zoology
axon guidance
fasciculation
midline
neocortex
mouse
Neuronal Growth Cones
Subplate Neurons
Cerebral-cortex
Normal Mouse
Connections
Organization
Projection
Pathway
Brain
Rat
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Unknown

Document type: Journal Article
Sub-type: Article (original research)
Collection: School of Biomedical Sciences Publications
 
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Created: Wed, 19 Sep 2007, 16:24:40 EST