title: Establishment of the Vertebrate Germ Layers.
abstract: The process of germ layer formation is a universal feature of animal development. The germ layers separate the cells that produce the internal organs and tissues from those that produce the nervous system and outer tissues. Their discovery in the early nineteenth century transformed embryology from a purely descriptive field into a rigorous scientific discipline, in which hypotheses could be tested by observation and experimentation. By systematically addressing the questions of how the germ layers are formed and how they generate overall body plan, scientists have made fundamental contributions to the fields of evolution, cell signaling, morphogenesis, and stem cell biology. At each step, this work was advanced by the development of innovative methods of observing cell behavior in vivo and in culture. Here, we take an historical approach to describe our current understanding of vertebrate germ layer formation as it relates to the long-standing questions of developmental biology. By comparing how germ layers form in distantly related vertebrate species, we find that highly conserved molecular pathways can be adapted to perform the same function in dramatically different embryonic environments.
authors.affiliation: Department of Cellular Biology, University of Georgia, Athens, GA, 30602, USA.
authors.forename: Wei-Chia
authors.initials: WC
authors.lastname: Tseng
authors.affiliation: Department of Cellular Biology, University of Georgia, Athens, GA, 30602, USA.
authors.forename: Mumingjiang
authors.initials: M
authors.lastname: Munisha
authors.affiliation: Department of Mathematics, University of Georgia, Athens, GA, 30602, USA.|Institute of Bioinformatics, University of Georgia, Athens, GA, 30602, USA.
authors.forename: Juan B
authors.initials: JB
authors.lastname: Gutierrez
authors.affiliation: Department of Cellular Biology, University of Georgia, Athens, GA, 30602, USA. dougan@uga.edu.
authors.forename: Scott T
authors.initials: ST
authors.lastname: Dougan
mesh_terms: D000818:Animals; D018507:Gene Expression Regulation, Developmental; D005855:Germ Layers / Q000254:growth & development* / Q000378:metabolism; D015398:Signal Transduction / Q000235:genetics; D013234:Stem Cells; D014714:Vertebrates / Q000254:growth & development* / Q000378:metabolism
keywords: Amniote; Amphibian; Ectoderm; Endoderm; Extraembryonic tissues; Fgf; Mesoderm; Morphogen; Nodal; Pander; TGF-beta; Teleost; Temporal gradient