| Dissertation |
Thesis (Ph.D.) --NUI, 2005 at Department of Anatomy, UCC. |
| Summary |
Radial glial cells have classically been viewed as a population of neuronal support cells, which provide a transient scaffold for migrating neurons in the central nervous system (CNS). Once these functions have been completed, radial glia were thought to shift towards the exclusive generation of astrocytes. However, at least in the cerebral cortex, recent reports have raised doubts about the distinction between radial glia and precursor cells by demonstrating that radial glia are themselves neuronal progenitors cells, thereby indicating multiple roles for radial glia in neurogenesis, neuronal migration guidance and gliogenesis. While much ongoing work is revealing radial glial cell functions in the cerebral cortex, their development and functions in the spinal cord are poorly understood. In the present study, radial glial cell development and lineage relationships in the spinal cord are investigated in vivo and in vitro. These findings suggest that there is a lineage progression from neuroepithelial cell through to astrocyte in the developing spinal cord. A population of radial cells, that resemble radial glial cells in morphology and are distinct from an earlier pseudostratified neuroepithelium, is revealed. These radial cells arise directly from the spinal cord neuroepithelium and are probably the progenitors of neurons and the earliest appearing radial glial cells. Few if any neurons appear to be derived from radial glial cells, which are instead the major sources of astrocytes in the spinal cord. Evidence for the non-radial glial cell origins of some white matter astrocytes is presented and subpopulations of postnatal astrocytes are described. This study also revealed a conservation of radial fibre periodicity throughout the rostrocaudal and dorsoventral axis of the spinal cord. In addition, the densities of radial glial processes vary spatially and temporally, correlating with the appearance of axon tracts. In addition, radial processes appear to form complex networks which surround and segregate the larger tracts such as the corticospinal tract and the cuneate and gracile fasciculi. |
| Subject |
Spinal cord -- Anatomy.
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| Collection |
Theses Ph.D.
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|
Theses Anatomy Department
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| Description |
167 p. : ill. ; 30 cm. |
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