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.

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

6. Ectoderm to Neuroectoderm: 20 days to 30 days

7. Rhombencephalic isthmus
Pontine flexure

9. BRAIN FLEXURES 4th week Cephalic/Midbrain flexure Cervical flexure
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

10. Pontine flexure

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

12. Basal, Alar, Roof & Floor plates

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

15. SPINAL NERVES

16. Neural Crest Cells

17. NEURAL CREST CELLS

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

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

21. Spina bifida occulta. Spina bifida cystica. Spina bifida
Spina bifida occulta Spina bifida cystica Spina bifida Meningomyelocele Myeloschisis

22. Acrania, Cerebral regression & Anencephaly

23. 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

25. THANK YOU