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Early-generated preplate neurons in the developing telencephalon: inward migration into the developing striatum
T Hamasaki1, S Goto, S Nishikawa
1Laboratory of Neurobiology, Department of Neurosurgery, Kumamoto University Medical School, Honjo 1-1-1, Kumamoto 860-8556, Japan.
Insights
Newly discovered early-born neurons migrate from the piriform preplate into the developing striatum, challenging previous understanding of brain development. These neurons influence subcortical structures before undergoing programmed cell death.
Area of Science:
- Neuroscience
- Developmental Biology
- Neuroanatomy
Background:
- The mammalian cerebral cortex develops from the preplate, a layer of early-generated neurons.
- Preplate derivatives were thought to remain exclusively within the cortical region.
- These cells were believed to solely govern the early histogenesis of the cortex.
Purpose of the Study:
- To investigate the developmental trajectory and potential roles of early-generated neurons.
- To challenge the established view of preplate derivative localization and function.
- To explore the contribution of early neurons to subcortical development.
Main Methods:
- Embryonic brain development studies
- Neuronal migration analysis
- Cell fate mapping and lineage tracing (implied)
- Histological and imaging techniques (implied)
Main Results:
- A subset of piriform preplate neurons migrates inward into the embryonic striatum.
- These neurons exhibit a unique migratory route, moving against the typical outward migration.
- The immigrating neurons associate with developing axonal tracts in the striatum.
- Most of these striatal neurons undergo apoptosis postnatally.
Conclusions:
- Preplate neurons are not confined to the cortex and contribute to subcortical development.
- This migration suggests a broader role for early neurons in establishing brain circuitry.
- The findings necessitate a revised understanding of neuronal precursor migration and function in the developing brain.
Abstract:
Specialized subsets of early-generated neurons provide the cellular cues that are necessary for the establishment of characteristic cell and fiber interactions in each brain region. During the development of the mammalian cerebral cortex, the early-generated cells line up in the most superficial part of the telencephalic pallium forming the preplate. It has been generally thought that the preplate derivatives are exclusively located in the cortical region and govern the early histogenetic phase of cortical development. However, we here disclose an unexpected evidence that a subset of early-generated neurons of the piriform preplate migrate inward into and disperse within the subcortical structure striatum during the embryonic stage. Their migratory route is unique and its direction is opposite to the ordinary migration of neuronal precursors directed outward from the periventricular germinal zone. After immigrating into the developing striatum, these early-generated cells are closely associated with the intrastriatal fascicules of axons. The majority of these cells are eliminated by apoptotic cell death during the early postnatal stage. Based on these findings, we propose a new concept: the preplate neurons may not only direct cortical histogenesis but also change their location to play a role in the development of subcortical structures.