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Neural tube-ectoderm interactions are required for trigeminal placode formation
M R Stark1, J Sechrist, M Bronner-Fraser
1Division of Biology, California Institute of Technology, Pasadena 91125, USA.
Development (Cambridge, England)
|October 23, 1997
Summary
This study identifies Pax-3 as a marker for ophthalmic placode development in vertebrates. Neuroectodermal signals are crucial for ophthalmic placode induction and maintenance, independent of neural crest cells.
Area of Science:
- Developmental biology
- Neuroscience
- Genetics
Background:
- Cranial sensory ganglia arise from ectodermal placodes and neural crest.
- Mechanisms of placode cell formation, invagination, and migration are poorly understood.
Purpose of the Study:
- To investigate the molecular mechanisms of vertebrate cranial placode development.
- To identify markers for placodal cells and analyze their developmental processes.
Main Methods:
- Utilized Pax-3 as a molecular marker for ophthalmic placode cells.
- Employed DiI labeling of surface ectoderm to track cell movements.
- Manipulated cranial neural crest presence and tissue interactions.
Main Results:
- Pax-3 expression marks ophthalmic placode cells from the 4-somite stage.
- Placodal invagination begins at the 13-somite stage and continues until trigeminal ganglion condensation.
- Neural crest cells are not essential for Pax-3 expression in placodes.
Conclusions:
- A diffusible signal from the neuroectoderm is required for ophthalmic placode induction and/or maintenance.
- Placode development can proceed independently of direct neural crest cell contribution.