[Neuroblastic migration: embryological aspects and mechanisms].
BACKGROUND
The migration of immature neurons of the cerebrum is genetically programmed from the primitive neuroepithelium before the end of the final mitotic cycle. The orientation of the mitotic spindle determines when a neuroepithelial cell is ready to start migration and the proportion of major genetic material it is destined to receive.


METHODS
The gene LIS1, defective in lissencephaly type 1 of Miller and Dieker, is expressed in the neuroepithelial cells, in the ependyma and the Cajal-Retzius neurons. These transitory fetal cells are the first neurons of the cerebral cortex. Most of the neurons of the cortical plate arrive by means of glial radial cells which guide them towards their destination. Cell adhesion molecules from the neuroblasts themselves, the glial radial cell, the extracellular matrix and perhaps the ependymal cells are important in adhering the neuroblasts to the glial radial cells. Genetic deficiency of these molecules results in defective migration. The mechanism of cellular movement is still not fully understood. Disorders of migration may also be induced by non-genetic factors, such as infarcts or other lesions which damage or destroy the glial radial fibres during the fetal period.
Sarnat
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Departamento de Neurologia, Universidad de Washington, Facultad de Medicina, Seattle 98103, USA. hsarna@chmc.org
D001921:Brain / Q000196:embryology*; D002448:Cell Adhesion / Q000502:physiology; D002465:Cell Movement / Q000502:physiology*; D006801:Humans; D009457:Neuroglia / Q000502:physiology*