Development of CNS 01
- 2. • Whole of nervous system is derived from ectoderm. The specific cell population of early ectoderm giving rise to CNS & special sense organs is termed as NEURAL ECTODERM.
- 3. DEVELOPMENT OF NEURAL TUBE
- 6. NEURULATION NEURAL PLATE (thickening of ectoderm overlying notochord) NEURAL GROOVE NEURAL TUBE
- 9. NEURAL CREST CELLS & ITS DERIVATIVES
- 12. NEURAL CREST DERIVATIVES 1. NEURONS OF DORAL NERVE ROOT GANGLIA 2. NEURONS OF SENSORY GANGLIA 5, 7,8, 9 & 10 CRANIAL NERVES 3. NEURONS OF SYMPATHETIC GANGLIA, THE PREAORTIC GANGLIA 4. NEURONS OF PARASYMPATHETIC GANGLIA OF CRANIAL NERVES 5. PARASYMPATHETIC GANGLIA OF GIT & GANGLIA RELATED TO PELVIC VISCERA 6. SCHWANN CELLS 7. SPECIFIC CELLS OF ADRENAL MEDULLA 8. CHROMAFFIN TISSUE 9. PIGMENT CELLS OF SKIN(Melanoblasts) 10. PIAMATER & ARACHNOID MATER
- 13. OTHER STRUCTURES DERIVED FROM NEURAL CREST CELLS 1. MESENCHYME OF DENTAL PAPILLA, ODONTOBLASTS & DENTINE 2. BONES OF FACE & PART OF VAULT OF SKULL 3. DERMIS, SMOOTH MUSCLE & FAT OF FACE & VENTRAL ASPECT OF NECK 4. MUSCLES OF CILIARY BODY 5. SCLERA & CHOROID OF EYE 6. SUBSTANTIA PROPRIA & POST. EPITH. OF CORNEA 7. CONNECTIVE TISSUE OF THYROID, PARATHYROID, THYMUS & SALIVARY GLANDS 8. DERIVATIVES OF 1, 2 & 3 PHARYNGEAL CARTILAGES 9. C- CELLS OF THYROID GLAND 10. CARDIAC SEMILUNAR VALVES & CONOTRUNCAL SEPTUM 11. SMOOTH MUSCLES OF BLOOD VESSELS OF FACE & FOREBRAIN 12. SATELLITE CELLS OF ALL SENSORY GANGLIA
- 14. NEURAL TUBE & ITS SUBDIVISIONS
- 17. FLEXURES • CERVICAL FLEXURE: at junction of rhombencephalon & spinal cord. • MESENCEPHALIC FLEXURE: in region of midbrain • PONTINE FLEXURE: at middle of rhombencephalon, dividing it into- metencephalon & myelencephalon. • TELENCEPHALIC FLEXURE: between telencephalon & diencephalon.
- 21. • Each of subdivisions of developing brain encloses a part of original cavity of neural tube. • The cavity of: Telencephalic vesicle becomes LATERAL VENTRICLE Diencephalon becomes THIRD VENTRICLE Mesencephalon forms AQUEDUCT Rhombencephalon forms FOURTH VENTRICLE. Its cotinuation in spinal cord is CENTRAL CANAL.
- 24. NEURAL TUBE DEFECTS A) NON CLOSURE OF NEURAL TUBE 1) POSTERIOR RACHISCHISIS 2) ANENCEPHALY 3) NON FUSION OF NEURAL TUBE ASSOCIATED WITH NON CLOSURE OF :- CRANIUM- CRANIUM BIFIDUM VERTEBRAL CANAL-SPINA BIFIDA
- 26. NON-CLOSURE OF NEURAL TUBE • POSTERIOR RACHISCHISIS- whole length of neural tube ramains unclosed • ANENCEPHALY- neural tube remains unclosed in region of brain
- 28. NEURAL TUBE DEFECTS B) OUTWARD BULGING OF NEURAL TUBE & COVERING MEMBRANES 1) Encephalocele- in brain 2) Myelocele- in spinal cord
- 29. OUTWARD BULGING OF NEURAL TUBE & COVERING MENINGES • SPINA BIFIDA OCCULTA • SPINA BIFIDA CYSTICA: 1) MENINGOCELE 2) MYELOMENINGOCELE
- 33. DEVELOPMENT OF SPINAL CORD
- 34. DEVELOPMENT OF SPINAL CORD
- 35. • With Alar Lamina growth, dorsal part of cavity obliterates forming- Post. Median Septum While ventral part of cavity forms Central Canal. • Further, Basal Lamina enlarges & projects on either side of midline forming Ant. Median Fissure.
- 36. • Nerve cells of: Basal Lamina Alar Lamina ↓ ↓ Neurons of: Ant. Grey Column Post. Grey column ↓ ↓ Axons grow out Axons forms to form Ant. Nerve Root. Ascending Tracts. ∞Dorsal Nerve Root formed from neural crest cells.
- 38. • Axons of neurons in Post. GRey column enters marginal layer forms Ascending Tracts. • Axons of cell developing in various parts of brain grow downwards to enter marginal layer forming Descending Tracts. • Marginal Layer: Asc. + Desc. Tracts= white matter. • Mantle layer: Alar Lamina forms Posterior grey column & Basal Lamina forms Ventral grey column.