neural crest cells

Examples of neural crest cells in the following topics:

• Development of the Integumentary System

  • The integumentary system develops from all embryonic layers (ectoderm, mesoderm, and neural crest cells).
  • Fetal skin forms from three layers: ectoderm, mesoderm, and neural crest cells.
  • Between 4 and 12 weeks, the basal cells divide repeatedly to form the stratified epithelium while the mesoderm forms the blood vessels and connective tissues.
  • Melanoblasts that form melanocytes migrate with neural crests cells to the epithelium and begin producing melanin prior to birth.

• Development of the Peripheral Nervous System

  • The peripheral nervous system develops from two strips of tissue called the neural crest, running lengthwise above the neural tube.
  • The sequence of stages from neural plate to neural tube and neural crest is known as neurulation .
  • Neural crest cells are a transient, multipotent, migratory cell population unique to vertebrates that gives rise to a diverse cell lineage including melanocytes, craniofacial cartilage and bone, smooth muscle, peripheral and enteric neurons and glia.
  • After gastrulation, neural crest cells are specified at the border of the neural plate and the non-neural ectoderm.
  • Subsequently, neural crest cells from the roof plate of the neural tube undergo an epithelial to mesenchymal transition, delaminating from the neuroepithelium and migrating through the periphery where they differentiate into varied cell types, including pigment cells and the cells of the PNS.

• Establishing Body Axes during Development

  • Primary neurulation divides the ectoderm into three cell types: the internally located neural tube, the externally located epidermis, and the neural crest cells, which develop in the region between the neural tube and epidermis but then migrate to new locations.
  • In the head, neural crest cells migrate, the neural tube closes, and the overlying ectoderm closes.
  • In the trunk, overlying ectoderm closes, the neural tube closes and neural crest cells migrate.
  • Three main ventral cell types are established during early neural tube development: the floor plate cells, which form at the ventral midline during the neural fold stage; as well as the more dorsally located motor neurons and interneurons.
  • These cell types are specified by the secretion of Shh from the notochord (located ventrally to the neural tube), and later from the floor plate cells.

• Somite Development

  • In the developing vertebrate embryo, somites are masses of mesoderm that can be found distributed along the two sides of the neural tube.
  • The mesoderm found lateral to the neural tube is called the paraxial mesoderm.
  • It is separate from the chordamesoderm underneath the neural tube.
  • As the primitive streak regresses and the neural folds gather preceding the formation of the neural tube, the paraxial mesoderm divides into blocks called somites.
  • Somites play a critical role in early development by participating in the specification of the migration paths of neural crest cells and spinal nerve axons.

• Embryonic Development

  • The first step in CNS development is primary neurulation that divides the ectoderm into three tissue regions, the neural tube, which is internally located, the epidermis, which is externally located, and the neural crest cells, which develop in the region between the neural tube and epidermis but then migrate to new locations.
  • The neural tube becomes patterned along the dorsal-ventral axis to establish defined compartments of neural progenitor cells, which will give rise to distinct classes of neurons.
  • Three main ventral cell types are established during early neural tube development, these include the floor plate cells , which form at the ventral midline during the neural fold stage, as well as the more dorsally located motor neurons and interneurons.
  • These cell types are specified by the secretion of Shh from the notochord (located ventrally to the neural tube), and later from the floor plate cells.
  • Shown is the dorsal root ganglion (green ellipsoid regions where cells express neurofilament) and the ventricular zone (red region where cells proliferate) as well as the neural tube with roof and floor plate.

• Clusters of Neuronal Cell Bodies

  • Ganglia are composed mainly of neuron cell bodies (somata) and dendritic structures.
  • Satellite glial cells are a type of glial cell that line the exterior surface of neurons in the peripheral nervous system (PNS) .
  • Satellite glial cells (SGCs) also surround neuron cell bodies within ganglia.
  • They are of a similar embryological origin to Schwann cells of the PNS, as they are both derived from the neural crest of the embryo during development.
  • Satellite cells also act as protective, cushioning cells.

• Development of Nervous Tissue

  • Embryonic neural development includes the birth and differentiation of neurons from stem cell precursors.
  • In vertebrates, the first sign of the nervous system is the appearance of a thin strip of cells along the center of the back, called the neural plate .
  • At this point the future CNS appears as a cylindrical structure called the neural tube, whereas the future PNS appears as two strips of tissue called the neural crest, running lengthwise above the neural tube.
  • The sequence of stages from neural plate to neural tube and neural crest is known as neurulation.
  • Induction of neural tissues causes formation of neural precursor cells, called neuroblasts.

• Development of Vision

  • The eye develops from the neural tube, the epidermis, and the periocular mesenchyme, which receives contributions from both the neural crest and mesoderm lineages.
  • First, an outpocketing of the neural tube occurs, creating optic vesicles.
  • Some cells in the lens vesicle will form the cornea and the lens vesicle will develop completely to form the definitive lens.
  • Iris is formed from the optic cup cells.
  • The eyes make their appearance before the closure of the anterior end of the neural tube.

• Gastrulation

  • Cells from the epiblast at the primitive streak undergo an epithelial to mesenchymal transition and ingress at the primitive streak to form the germ layers.
  • The ectoderm gives rise to the epidermis, and also to the neural crest and other tissues that will later form the nervous system.
  • Following gastrulation, the cells in the body are either organized into sheets of connected cells (as in epithelia), or as a mesh of isolated cells, such as mesenchyme.
  • The differentiation of cells into one of three types (endodermal, mesodermal, or ectodermal).
  • Although gastrulation patterns exhibit enormous variation throughout the animal kingdom, they are unified by the five basic types of cell movements that occur during gastrulation:

• Neurulation

  • During gastrulation cells migrate to the interior of the embryo, forming the three germ layers: the endoderm (the deepest layer), the mesoderm (the middle layer), and the ectoderm (the surface layer) from which all tissues and organs will arise.
  • This results in a strip of neuronal stem cells that runs along the back of the fetus.
  • The neural plate folds outwards to form the neural groove.
  • In general, it entails the cells of the neural plate forming a cord-like structure that migrates inside the embryo and hollows to form the tube.
  • Transverse sections that show the progression of the neural plate into the neural tube.