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Does hair cell differentiation predate the vertebrate appearance?
Paolo Burighel1, Federico Caicci, Giovanna Zaniolo
1Department of Biology, University of Padova, Via U. Bassi 58/B 35131, Italy. paolo.burighel@unipd.it
Brain Research Bulletin
|March 12, 2008
Summary
Ancestral chordates may have possessed precursors to vertebrate hair cells, specifically within tunicates. The coronal organ in ascidians shows striking similarities to vertebrate hair cells, suggesting early chordate origins.
Area of Science:
- Evolutionary biology
- Comparative anatomy
- Developmental biology
Background:
- Chordates share a common ancestor with key body plan features.
- Tunicates are increasingly recognized as the sister group to vertebrates.
- Tunicates possess sensory structures analogous to vertebrate placodes and neural crest derivatives.
Purpose of the Study:
- To investigate whether ancestral chordates had precursors to vertebrate hair cells.
- To examine the morphology and potential homology of the ascidian coronal organ with vertebrate hair cells.
Main Methods:
- Comparative analysis of sensory structures in tunicates and vertebrates.
- Morphological examination of the coronal organ in ascidian species, including Botrylloides leachi.
Main Results:
- Ascidian coronal organs consist of secondary mechanosensory cells with supporting cells.
- Coronal cells exhibit varying morphologies, including multiciliate and apical apparatus with stereovilli.
- The coronal organ's structure and presumed origin resemble vertebrate hair cells.
Conclusions:
- The coronal organ in tunicates provides evidence for early chordate origins of vertebrate hair cell precursors.
- Morphological similarities suggest a shared evolutionary heritage for these sensory structures.
- Further studies on diverse ascidian species are ongoing to confirm these findings.
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