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Cell proliferation in the lamprey central nervous system
Ivonne Vidal Pizarro1, Gary P Swain, Michael E Selzer
1University of Pennsylvania, Institute of Neurological Sciences, Philadelphia, Pennsylvania 19104, USA.
The Journal of Comparative Neurology
|December 25, 2003
Summary
Lamprey central nervous system (CNS) cell proliferation is seasonal, with higher mitosis rates in summer. Most cell division contributes to gliogenesis, not neurogenesis, mainly in the ependyma.
Area of Science:
- Neuroscience
- Developmental Biology
- Cell Biology
Background:
- Axon regeneration occurs in lamprey central nervous system (CNS) after injury.
- Cell proliferation rates in the uninjured lamprey CNS are not well understood.
Purpose of the Study:
- To determine the prevalence and patterns of cell division (mitosis) in the lamprey CNS.
- To investigate potential seasonal variations and cell types involved in CNS proliferation.
Main Methods:
- Bromodeoxyuridine (BrdU) labeling to identify newly synthesized DNA in cells.
- Quantification of labeled cells (mitotic index) in the rhombencephalon and spinal cord.
- Immunohistochemistry using antibodies for glial and neuronal markers.
Main Results:
- Mitotic activity showed seasonal variation, peaking in summer with a transient spike.
- Baseline mitotic indices were approximately 0.15% in the rhombencephalon and 0.20% in the spinal cord.
- Proliferating cells were primarily glial (identified by glial keratin), with minimal evidence of neurogenesis.
Conclusions:
- Neurogenesis is uncommon in the lamprey CNS.
- Baseline gliogenesis occurs mainly in the ependyma, with contributions from nonependymal regions.
- A summer spike in mitosis, particularly in the rhombencephalon's ependyma and the spinal cord, suggests seasonal regulation of gliogenesis.