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Spinal Cord Dev


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Spinal Cord Dev

  1. 1. EMBRYOLOGY Neural Tube By Dr. Dalia Saleh
  2. 2. Second Week Epiblast Hypoblast Amniotic cavity Yolk sac cavity Dr. Dalia Saleh (Anatomy Dept)
  3. 3. Third Week Primitive node Primitive streak Intra embryonic mesoderm Notochord Dr. Dalia Saleh (Anatomy Dept)
  4. 4. Neural Tube Arises from the ectoderm overlying the notochord Gives rise to the brain and spinal cord Dr. Dalia Saleh (Anatomy Dept)
  5. 5. Neural Tube Formation The notochord induces the ectoderm above it which thickens to form the neural plate Dr. Dalia Saleh (Anatomy Dept)
  6. 6. Neural Tube Formation The neural plate folds to form neural groove with prominent neural folds The neural folds approach each other with deepening of the neural groove Dr. Dalia Saleh (Anatomy Dept)
  7. 7. Neural Tube Formation The neural folds fuse and a neural tube is formed The tube, then, separates from the overlying ectoderm Dr. Dalia Saleh (Anatomy Dept)
  8. 8. Neural Tube Closure Closure of the neural tube begins in the future neck region (4th somite). Then, proceeds cranially and caudally. Dr. Dalia Saleh (Anatomy Dept)
  9. 9. Neural Tube Closure The most cranial and caudal ends of the tubes still open as • Anterior neuropore • Posterior neuropore The anterior pore will close @ day 25 the posterior @ day 27 The lumen of the tube ventricles of the brain and central canal of spinal cord Dr. Dalia Saleh (Anatomy Dept)
  10. 10. Development of the Brain 3 primary vesicles @ 4th week: Prosencephalon Mesencephalon Rhombencephalon Dr. Dalia Saleh (Anatomy Dept)
  11. 11. Development of the Brain 5 secondary vesicles @ 6th week: Prosencephalon Telencephalon Diencephalon Mesencephalon Rhombencephalon Metencephalon Mylencephalon Dr. Dalia Saleh (Anatomy Dept)
  12. 12. Development of the Spinal Cord The cells of the neural tube migrate to form the mantle layer gray matter which differentiates into An alar plate, mostly sensory neurons A basal plate, mostly motor neurons. Separated by sulcuc limitans Dr. Dalia Saleh (Anatomy Dept)
  13. 13. Development of the Spinal Cord The cells of the mantle layer have axons which collect in the marginal layer white matter Dr. Dalia Saleh (Anatomy Dept)
  14. 14. Histogenesis of the Spinal Cord First, the neural tube is lined by neuroepithelial cells They then divide to give: Neuroblasts apolar, unipolar, bipolar, multipolar Glioblasts astrocytes, oligodendrocytes Ependymocytes Dr. Dalia Saleh (Anatomy Dept)
  15. 15. Neural Crest Cells Originate from cells of neural folds. Lie between the neural tube and surface ectoderm. Dr. Dalia Saleh (Anatomy Dept)
  16. 16. Neural Crest Cells They, then, migrate to new locations many derivatives G G A M E A M E S S Ganglion cells (DRG, Cranial sensory, Autonomic) Arachnoid and pia maters Melanocytes, Mesenchyme of the pharyngeal arches Enteric ganglia Schwann cells, Suprarenal medulla cells Dr. Dalia Saleh (Anatomy Dept)
  17. 17. Tissues around The Spinal Cord Neural crest pia and arachnoid maters Mesderom Microglial cells Mesenchyma dura mater Somites become vertebrae. Dr. Dalia Saleh (Anatomy Dept)
  18. 18. Dr. Dalia Saleh (Anatomy Dept)
  19. 19. Spinal Cord Positioning @ 3rd month same length as vertebral canal @ Birth Spinal cord terminates at 3rd lumbar vertebra @ Adult spinal cord terminates at the level of L1 Dr. Dalia Saleh (Anatomy Dept)