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DEVELOPMENT OF CNS

DEVELOPMENT OF CNS. By Dr S amina A njum. NERVOUS SYSTEM. The central nervous system (CNS): - Brain and spinal cord The peripheral nervous system (PNS): - Neurons outside the CNS

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DEVELOPMENT OF CNS

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  1. DEVELOPMENT OF CNS By Dr Samina Anjum

  2. NERVOUS SYSTEM • The central nervous system (CNS): - Brain and spinal cord • The peripheral nervous system (PNS): - Neurons outside the CNS - Cranial and spinal nerves that connect the brain and spinal cord with peripheral structures • The autonomic nervous system (ANS): - Has parts in both the CNS and PNS.

  3. Neurulation CNS appears at the beginning of 3rd week of development.

  4. Closure of Neural Tube • Day 25 Rostral neuropore closes • Day 28 Caudal neuropore closes

  5. Ectoderm to Neuroectoderm: 20 days to 30 days

  6. Rhombencephalic isthmus Pontine flexure

  7. BRAIN FLEXURES Rhombencephalic isthmus 4th week • Cephalic/Midbrain flexure • Cervical flexure • Pontine flexure • Flexures cause variation in outline of T.S of brain at various levels & in position of grey & white substance

  8. Pontine flexure

  9. Development of Spinal CordNeuroepithelial, Mental and Marginal layers Neuroepithelium With Junctional complexes at the lumen (White matter Of S.C) Neuroblasts (Gray matter of S.C)

  10. Basal, Alar, Roof & Floor plates

  11. Histological Differentiation Nerve cells, Glial cells & Neural crest cells Vascular Transient dendrite Marginal layer Lie b/w Blood vessels and neurons

  12. SPINAL NERVES

  13. Neural Crest Cells

  14. NEURAL CREST CELLS

  15. MyelinationSpinal cord begins in 4th month---1st year Tracts in N.S myelinate when they start functioning Neurilemmal sheath PNS CNS

  16. Positional Changes in Spinal Cord Subarachnoid space 3rd month End of 5th month New born Adult

  17. Spina bifida occulta Spina bifida cystica Spina bifida Meningomyelocele Myeloschisis

  18. Acrania, Cerebral regression & Anencephaly

  19. PITUITARY GLAND-ECTODERMAL Rathke’s pouch (Ectodermal out pocketing of stomodeum) embryo is 3 weeks End of 2nd month Looses its connection with oral cavity

  20. THANK YOU

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