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Segmentation and compartition in the early avian hindbrain
1MRC Centre for Developmental Neurobiology, King's College London, Guy's Hospital Campus, London SE1 1UL, UK. andrew.lumsden@kcl.ac.uk
Mechanisms of Development
|August 7, 2004
Summary
Vertebrate hindbrain segmentation into rhombomeres is a true metameric organization, crucial for brain development and evolution. Avian embryos are key to understanding these segments' cellular and molecular basis.
Area of Science:
- Developmental Biology
- Neuroscience
- Evolutionary Biology
Background:
- Early 20th-century embryologists debated the significance of transient hindbrain bulges, known as rhombomeres.
- Conflicting views existed on whether rhombomeres represented true segments or inconsequential structures in vertebrate brain development and head evolution.
Purpose of the Study:
- To review the contribution of avian embryos to understanding hindbrain rhombomere development.
- To elucidate the morphology, neuronal architecture, and cellular/molecular mechanisms of rhombomere segmentation and identity.
Main Methods:
- Modern techniques including immunohistochemistry, in situ hybridization, gene expression manipulation (electroporation), and grafting.
- Axonal tracing, single-cell labeling, and electrophysiological studies in avian embryos.
Main Results:
- Modern studies confirm the hindbrain possesses a truly metameric cellular organization.
- Rhombomere segmentation is vital for establishing the functional organization of the hindbrain.
- Avian embryos, due to accessibility and anatomy, have been pivotal in these discoveries.
Conclusions:
- Rhombomeres are confirmed as true metameric units, essential for hindbrain development and function.
- Segmentation allows for the allocation of precursor cells and the emergence of specific segmental identities.
- The avian embryo model provides critical insights into the mechanisms governing hindbrain segmentation and segmental identity.