The neural crest as a fourth germ layer and vertebrates as quadroblastic not triploblastic

  title={The neural crest as a fourth germ layer and vertebrates as quadroblastic not triploblastic},
  author={Brian K. Hall},
  journal={Evolution \& Development},
  • B. Hall
  • Published 1 February 2000
  • Biology
  • Evolution & Development
Next to cells, germ layers—the fundamental embryonic celllayers from which tissues and organs form—are the mostlong-standing units of structural organization of the embryosof multicellular animals (metazoans). First identified inchicken embryos by Pander in 1817, the history of germ lay-ers through the nineteenth century was one of increasing ap-preciation of their generality and importance:• layers equivalent to those in the chick were found byRathke (1825) in a decapod crustacean;• von Baer… 

Germ layers, the neural crest and emergent organization in development and evolution

The discovery that ectodermal neural crest gave rise to mesenchyme and the controversy generated by that finding are discussed, as well as germ layers (including the neural crest) as emergent levels of organization in animal development and evolution that facilitated major developmental and evolutionary change.

Germ Layers

All other animals are triploblastic, as endoderm and ectoderm interact to produce a third germ layer, called mesoderm, which will give rise to every organ in the body.

Sources 1

All other animals are triploblastic, as endoderm and ectoderm interact to produce a third germ layer, called mesoderm, which will give rise to every organ in the body.

Neural crest cells and the community of plan for craniofacial development: historical debates and current perspectives.

This chapter describes how discussions surrounding the neural crest threatened the germ layer theory, upended traditional schemes of vertebrate head organization, challenged assumptions about morphological conservation and homology, and redefined concepts on mechanisms of craniofacial patterning.

It's about time for neural crest

Buitrago-Delgado et al. (3) provide further support for the statement that neural crest cells uniquely retain pluripotent stem cell programming until later in development than the three classic germ layers.

The neural crest and neural crest cells: discovery and significance for theories of embryonic organization

  • B. Hall
  • Biology
    Journal of Biosciences
  • 2008
An overview of the major phases of investigation into the neural crest and the major players involved is provided, how the origin of the Neural crest relates to theorigin of the nervous system in vertebrate embryos is discussed, the impact on the germ-layer theory of the discovery of the neural peak and of secondary neurulation are discussed, and evidence ofThe neural crest as the fourth germ layer is presented.

On the evolutionary origins and regionalization of the neural crest

The Generation of a Candidate Axial Precursor in Three Dimensional Aggregates of Mouse Embryonic Stem Cells

A novel culture system of small, threedimensional aggregates of ESCs (gastruloids) that can recreate the events of early post-implantation development, including axial elongation morphogenesis is presented.



Germ Layers and the Germ-Layer Theory Revisited

Germ layers are part of the foundation of the understanding of animal organization and have been classified as mono-, diplo-, or triploblastic, i.e., as having one, two, or three germ layers, for 124 years.

The Origin of Animal Body Plans

Economic historians make a useful distinction between inventions and innovations (inven- tions that succeed within an economy). Applying this distinction to the evolutionary novelties of the Cambrian

A Developmental Model for Evolution of the Vertebrate Exoskeleton and Teeth

An exoskeleton is extensive in the head, trunk, and tail of agnathan and gnathostome fishes, where it forms a thick, rigid armor in most fossil fishes, although many only have a covering of separate

Some problems with typological thinking in evolution and development

The aim in this article is to consider the manifestations of typologism in evolutionary developmental biology, and some of the problems associated with it.

The Neural Crest in Development and Evolution

  • B. Hall
  • Biology
    Springer New York
  • 1999
This work has shown that not only the structure of the Tournaisian distribution but also the distribution of Tournaiocytes in response to selection has changed over the course of evolutionary time.

XV. On the anatomy and physiology of cordylophora, a contribution to our knowledge of the Tubularian zoophytes

Though the attention of several physiologists has been directed to the Tubularian Zoophytes, and though the elucidation of many points of interest in their structure and in the physiological

XXII. On the anatomy and the affinities of the family of the medusæ

  • T. Huxley
  • History
    Philosophical Transactions of the Royal Society of London
  • 1849
It is the intention to endeavour to supply the want of patience or ability on the part of the observers in the present paper, and to suggest a clue in unravelling many complexities, at first sight not very intelligible.


This review deals with the following seven aspects of vertebrate skeletogenic and odontogenic tissues: innervation, chemoreception, histology, histopathology, “soft” and “hard” tissues.