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Assessing Signaling Properties of Ectodermal Epithelia During Craniofacial Development
Published on: March 24, 2011
Neural crest patterning and the evolution of the jaw.
C B Kimmel1, C T Miller, R J Keynes
1Institute of Neuroscience, University of Oregon, Eugene 97403-1254, USA. kimmel@uoneuro.uoregon.edu
Journal of Anatomy
|August 29, 2001
Summary
The evolution of vertebrate jaws likely involved cranial neural crest cells migrating to form gill supports in ancient jawless vertebrates (agnathans). This developmental process explains the structural changes observed in jawed vertebrates (gnathostomes).
Area of Science:
- Developmental Biology
- Evolutionary Biology
- Comparative Anatomy
Background:
- The origin of the jaw in jawed vertebrates (gnathostomes) remains a complex evolutionary question.
- Understanding the role of cranial neural crest cells in vertebrate evolution is crucial for deciphering early vertebrate anatomy.
- Previous hypotheses regarding jaw evolution have faced challenges in explaining topological changes in gill structures.
Purpose of the Study:
- To investigate the connection between cranial neural crest cell behavior during development and the evolution of the vertebrate jaw.
- To provide a developmental explanation for the observed differences in gill and jaw support structures between jawless (agnathan) and jawed (gnathostome) vertebrates.
- To re-evaluate the hypothesis that gnathostome jaws evolved from the gill cartilages of ancient agnathans.
Main Methods:
- Comparative analysis of cranial neural crest cell migration patterns in zebrafish and other gnathostomes.
- Examination of the arrangement of cranial neural crest and head mesoderm in developing pharyngeal segments (branchiomeres) across diverse vertebrates, including lampreys.
- Application of von Baerian principles to explain topological changes in gill structures.
Main Results:
- Detailed description of cranial neural crest ectomesenchyme migration in zebrafish.
- Analysis of postmigratory crest and head mesoderm arrangement in nascent branchiomeres of various gnathostomes and lampreys.
- Identification of developmental patterns consistent with a transformation of gill supports into jaw supports.
Conclusions:
- Cranial neural crest cell behavior during development offers a plausible explanation for the evolution of the vertebrate jaw.
- The study supports the hypothesis that jaw supports in gnathostomes originated from branchiomeric cartilages of ancient jawless ancestors.
- A von Baerian developmental framework helps resolve the inside-outside topological shift of gills and their supports between agnathans and gnathostomes.
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