neural crest

Examples of neural crest in the following topics:

• 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.
  • 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 .
  • After gastrulation, neural crest cells are specified at the border of the neural plate and the non-neural ectoderm.
  • The neural tube will give rise to the central nervous system, while the neural crest will give rise to the peripheral nervous system.

• 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.
  • Melanoblasts that form melanocytes migrate with neural crests cells to the epithelium and begin producing melanin prior to birth.

• 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.
  • The edges of the neural plate start to thicken and lift upward, forming the neural folds.
  • 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.
  • (Neural tube is in green. )

• Development of Nervous Tissue

  • Embryonic neural development includes the birth and differentiation of neurons from stem cell precursors.
  • As development proceeds, a fold called the neural groove appears along the midline.
  • 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.

• Clusters of Neuronal Cell Bodies

  • 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.

• Glossopharyngeal (IX) Nerve

  • The motor division of the glossopharyngeal nerve is derived from the basal plate of the embryonic medulla oblongata, while the sensory division originates from the cranial neural crest.

• Gastrulation

  • The ectoderm gives rise to the epidermis, and also to the neural crest and other tissues that will later form the nervous system.

• Development of Vision

  • The eye forms from the neural tube, epidermis, and periocular mesenchyme, with sequential inductions of tissue during development.
  • 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.
  • The optic cup then delaminates into two layers: the neural retina and the retinal pigment epithelium.
  • The eyes make their appearance before the closure of the anterior end of the neural tube.

• 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 neural groove gradually deepens as the neural folds become elevated, and ultimately the folds meet and coalesce in the middle line and convert the groove into a closed tube, the neural tube or neural canal, the ectodermal wall of which forms the rudiment of the nervous system.
  • 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 edges of the neural plate start to thicken and lift upward, forming the neural folds.
  • The center of the neural plate remains grounded allowing a U-shaped neural groove to form.
  • The neural folds pinch in towards the midline of the embryo and fuse together to form the neural tube.