neurulation

• What is neurulation?

  Formation of vertebrae in the nervous system
• What is the process involved in neurulation?

  Neural plate formation and infolding to form neural tube
• What signals the ectoderm to form the neural plate?

  Notochord
• From which layer is the neural plate derived?

  Neuroectoderm
• Where does the notochord arise from?

  Mesoderm
• What does the neural tube arise from?

  Ectoderm
• When does the development of the notochord occur?

  At week 3
• How is the notochordal process formed?

  Mesodermal cells migrate cranially in midline
• What does the notochordal plate develop into?

  Notochord
• What induces the development of the neural tube?

  Notochord
• What happens to the neural plate during neural tube development?

  It folds in on itself
• What does the neural tube differentiate into?

  Brain and spinal cord
• What do neural crest cells form after migrating from the neural tube?

  Peripheral nervous system (PNS)
• What occurs during the lateral folding of the neural plate?

  Fusion of neural folds
• When does the anterior neuropore close?

  At day 24
• When does the posterior neuropore close?

  At day 26
• What is the role of bone morphogenetic protein in neural tube development?

  It is an important inducting agent
• What are the derivatives of neural crest cells?

  • Spinal ganglia
  • Ganglia of autonomic nervous system
  • Ganglia of some cranial nerves
  • Sheaths of peripheral nerves
  • Meninges of brain and spinal cord
  • Melanocytes
  • Suprarenal medulla
  • Skeletal and muscular components of head
• From which mesoderm do somites form?

  Paraxial mesoderm
• How many pairs of somites are formed by the 5th week of development?

  42-44 pairs
• What are the two components of a somite?

  Sclerotome and dermomyotome cells
• What do sclerotomes form?

  Cartilage and bone of axial skeleton
• What do myotomes form?

  Muscles of rib cage and limbs
• What do dermatome cells contribute to?

  Connective tissue of dermis
• What does the notochord exist as in adults?

  Nucleus pulposus of intervertebral discs
• What do inductive signals from the notochord stimulate?

  Conversion of surface ectoderm into neural plate
• What are the primary brain vesicles?

  • Prosencephalon (forebrain)
  • Mesencephalon (midbrain)
  • Rhombencephalon (hindbrain)
• What are the features of the spinal cord?

  Cranial neuropore, pericardial bulge, otic placode, caudal neuropore
• What do ependymal cells form in the brain and spinal cord?

  Marginal layer and mantle layer
• What does the mantle layer divide into?

  Alar plate and basilar plate
• What is the function of the alar plate?

  Receives axons from DRG (dorsal root ganglia)
• What does the basilar plate contain?

  Cell bodies of motor neurons
• What is a teratogen?

  Agent causing malformation of an embryo
• When is the highest risk for teratogen exposure?

  Between 3-5 weeks of embryonic period
• What are examples of chemical teratogens?

  • Lithium
  • Amphetamines
  • Alcohol
  • Organic mercury / lead
• What are examples of physical teratogens?

  • X-rays
  • Hyperthermia
• What are examples of infectious teratogens?

  • Rubella virus
  • Herpes simplex virus
  • Syphilis
  • Toxoplasmosis
• What are examples of hormonal teratogens?

  • DES
  • Maternal diabetes / obesity
• What are neural tube defects?

  Most common congenital abnormality
• When do neural tube defects arise?

  During week 3-4