1 / 71

Jittipan Chavadej,Ph.D.

EMBRYOLOGY NERVOUS SYSTEM. Jittipan Chavadej,Ph.D. Dept. of Anatomy,Fac. of Science, Mahidol University. September,2000. Diagrams showing formation of the neural groove, neural tube and neural crest. Neural tube-neural crest. Neural tube-brain & spinal cord.

lucien
Download Presentation

Jittipan Chavadej,Ph.D.

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. EMBRYOLOGY NERVOUS SYSTEM Jittipan Chavadej,Ph.D. Dept. of Anatomy,Fac. of Science, Mahidol University September,2000

  2. Diagrams showing formation of theneural groove, neural tube and neural crest

  3. Neural tube-neural crest Neural tube-brain & spinal cord Neural crest-most components of PNS -non-neural component in the body and head.

  4. Fundamental processes in Nervous system formation • Induction-Proliferation • Migration-Differentiation • Pattern formation • Intercellular communication • Stabilization or Elimination • Development of integrated pattern

  5. ChangesinGrossStructureof NS • Closure of neural tube • 24th-day -cranial neuropore • 26th-day -caudal neuropore • Cephalic end-primary brain vesicles • -procencephalon • -mesencephalon • -rhombencephalon • Spinal cord

  6. 3-wk. Embryo: - C shape - cephalic flexure (mesencephalon) - cervical flexure (hind brain&spinal cord) 5-wk. Embryo : - procencephalon-Telen., Dien. -mesencephalon -rhombencephalon-Meten., Myelen.

  7. A-lateral view of the brain vesicles and part of spinal cord. B-diagram showing the cavities of the three brain vesicles and spinal cord

  8. Diencephalon - optic vesicles Mesencephalon - sharply bend by cephalic flexure Rhombencephalon - Pontine flexure thin roof

  9. Basic anatomy of the five-part human brain

  10. Histogenesis within Nervous System • 2 major cell lineages • - Neuronal progenitor cell neurons • - Glial progenitor cell astrocyte, oligodrendrocyte, ependyma (neural tube) *Microglia-enter CNS from outside

  11. Cell lineages in the developing central nervous system

  12. Neuron-large cell body -long processe -axon-carry signals to targets -dendrites-receive input Neurons need to “ reach out and touch “ each other by forming synapses to survive.

  13. Development of nervous system components

  14. Formation of Zones 1. Ventricular zone-ependymal cells become epithelial lining of central canal 2. Mantle zone-neuroblast cells become gray matter of the CNS 3. Marginal zone-neuronal processes become white matter of the CNS

  15. Formation of zones & fundamental organization of the developing neural tube Note: -ependymal zone -mantle zone -marginal zone

  16. Fundamental Organization of Neural tube Dorsal portion/Alar plate/sensory <---Sulcus limitans Ventral portion/Basal plate/motor Roof plate - Floor plate

  17. A-development of regional specialization across the neural tube. B-formation of the spinal cord

  18. Spinal cord formation ** Basic plan of neural tube is preserved in spinal cord ** • Mantle zone = H-shape of gray matter with central canal • Marginal zone = White matter -->>myelinated nerve fibers

  19. Spinal cord - PNS Ventral aspect • Neuroblasts of basal plate ->> outgrowth of axons -->ventral nerve root Dorsalaspect • Thin processes of neuroblast of spinal ganglion-->dorsal nerve root

  20. Development of a peripheral nerve A-showing motor axon, growing fiber of nerve cell in DRG. B-showing ventral motor and dorsal sensory root joining to form the trunk of spinal nerve

  21. Myelination - in CNS -->> oligodendroglia - in PNS -->> Schwann cell

  22. Gross change of spinal cord • 6-wk.-->full length of vertebral column • 8-wk.-->end ~Co4 • 14-wk.-->end ~S1 • 23-wk.-->end ~L4 • Birth-->end ~L3 • Adult--> end~L2-3-filum terminale &cauda equina

  23. Functional components Dorsal alar horn = Afferent neurons • 2 functional categories: • -GSA(soma,body) & GVA(viscera) Ventral basal horn =Efferent neurons • 2 functional categories: GSE & GVE

  24. Dorsal alar plate-sensory horn of spinal cord Ventral basal plate-motor horn of spinal cord

  25. Brain Formation • The original organization of neural tube is altered in the formation of many regions of the brain. • Nerve cells form concentrated collections called nuclei in the brain

  26. Dilatations of the central lumen form ventricles in the brain • -lateral ventricle-> Telen. • -third ventricle-> Dien. • -cerebral aqueduct-> Midbrain • -fourth ventricle-> Hindbrain * CSF - choroid plexus

  27. A Development of the ventricular system of the brain A-early embryo B-during expansion of cerebral hemisphere C-postnatal morphology of ventricular system

  28. Formation of specific brain regions Rhombencephalon - Metencephalon - Myelencephalon Medulla oblongata-transitional zone *-major alteration --> 4th ventricle

  29. Expansion of roof plate- 4th ventricle Basal plate&Alar plate in brainstem Basal plate-->close to midline <---Sulcus limitans Alar plate--> lateral

  30. Alar and basal plates in myelencephalon showing the position of nuclear groups at different stages of development

  31. Basal plate contains three motor nuclei -medial somatic efferent gr.=SE -intermediate special visceral efferent gr.=SVE -lateral general visceral efferent gr.=GVE

  32. Alar plate contains sensory nuclei *-most lateral special somatic afferent gr.=SSA general somatic afferent gr.=GSA *-intermediate special visceral afferent gr.=SVA *-medial general visceral afferent gr.=GVA

  33. Special functional categories of cranial nuclei in the brainstem

  34. Motor and sensory nuclear groups in the basal and alar plates of caudal part of metencephalon

  35. The development of the cerebellum.- Dorsal view Note: 3 apertures - Foramen of Magendie(1-median) -Foramen of Luschka(2-lateral)

  36. Formation of the cerebellum or cerebrum involves formation of multiple neuronal layers in the cortex There is a second wave of proliferation fron the inner ventricular layer-->Germinal layerand give riseto cerebellar cortex

  37. A-D=development of cerebellum A&B=development of cerebellar cortex

  38. Glia play an important role in migration of cortical neurons Radial glia-->for guidance neurons to their destination The external cortical neurons-layers * The cerebellar hemispheres undergo extensive folding = Folia

  39. Radial glial cells and their association with peripherally migrating neurons during development of the brain

  40. DEVELOPMENT of Nervous System (cont.) Dr. Jittipan Chavadej Anatomy Department yr,2000

  41. Mesencephalon The alar region forms 4 swellings called corpora quadrigemina The ventral region forms -gray matter in tegmentum -white matter in cerebral peduncles

  42. Dorsal view of the midbrain & hindbrain

  43. Colliculi =relay nuclei for auditory & visual systems Tegmentum -cranial motor nuclei -2 prominent relay nuclei=red nucleus & substantia nigra Cerebral peduncle=fiber tracts from cerebrum > cerebellum > spinal cord

  44. Cross section-early&later developing mesencephalon (blue-sensory, red-motor)

  45. Forebrain-->dien. & telencephalon Dien. forms midline brainstem regions from its alar plate-contain relay nuclei. Dorsal -thalamus & epithalamus Ventral -hypothalamus

  46. Medial surface & X-section of prosencephalon. Note:corpus striatum bulgefrom the floor of lateral ventricle

  47. A -medial surface of telencephalon & diencephalon B -X-section Note:thalamus,hypothalamus & corpus striatum

  48. Midline -epiphysis Pituitary gl.-downgrowth of hypotha. + upgrowth of pharyngeal ectoderm *Craniopharyngioma-remnant of Rathke’s pouch

More Related