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30.6B: Development of the Peripheral Nervous System

  • Page ID
    8425
  • [ "article:topic" ]

    The peripheral nervous system develops from two strips of tissue called the neural crest, running lengthwise above the neural tube.

     

    LEARNING OBJECTIVES

     

    Describe peripheral nervous system development

     

    KEY TAKEAWAYS

    Key Points

     

    • 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. The inner portion of the neural plate is destined to become the central nervous system (CNS), while the outer portion will become the peripheral nervous system (PNS).
    • Neurulation (neural development) progresses with the formation of the neural groove which closes to form the neural tube and neural crest.
    • Neural crest cells from the roof plate of the neural tube migrate through the periphery where they differentiate into varied cell types, including pigment cells and the cells of the PNS.

     

    Key Terms

     

    • neurulation: The process by which the beginnings of the vertebrate nervous system is formed in embryos.
    • neural plate: A thick, flat bundle of ectoderm formed in vertebrate embryos after induction by the notochord.
    • neural crest: A strip of ectodermal material in the early vertebrate embryo inserted between the prospective neural plate and the epidermis.

    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. The inner portion of the neural plate (along the midline) is destined to become the central nervous system (CNS), the outer portion the peripheral nervous system (PNS). As development proceeds, a fold called the neural groove appears along the midline. This fold deepens and then closes up at the top. 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.

    image

     

    Formation of the Fetal Nervous System: The neural tube will give rise to the central nervous system, while the neural crest will give rise to the peripheral nervous system. This diagram shows the epidermis, neural fold, and convergence.

    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. During neurulation, the borders of the neural plate, also known as the neural folds, converge at the dorsal midline to form the neural tube. 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. The emergence of the neural crest was important in vertebrate evolution because many of its structural derivatives are defining features of the vertebrate clade.