1. 1)Neural Tube: Wall is formed by neuroepithelial cells(pseudost.epithelium) 2)Closure of neural tube: Proliferation of neuroepi.cells Form.of neuroepithelial cell layer 3)Formation of Mantle layer: Neuroepithelial cells-Neuroblasts- their cell bodies-GREY MATTER Of sp.cord 4)Formation of Marginal layer: Nerve fibres of neuroblasts-WHITE MATTER of sp.cord

2. Basal Alar Roof Floor 3. Ventrally formed In Mantle layer Form motor areas of sp.cord- Anterior horn Their nerve fibres pass through the marginal layer and emerge as ventral roots of spinal nerve 4. Form dorsal sensory areas of spinal cord Nerve fibres penetrate marginal zone and ascend or descend for several levels to form Association neurons 5. Between alar and basal plates 6. Present in midline region Contain no neuroblasts Serve as pathways for nerve fibres from one side to the other 7. Glioblasts are formed from neuroepithelial cells after the form.of neuroblasts has ceased Supporting cells Pass through all layers of spinal cord IN MANTLE LAYER: Differentiate to form Protoplasmic astrocytes & Fibrillar astrocytes(Nerve regeneration) IN MARGINAL LAYER: Differentiate to form oligodendrocytes (Myelinate ascending&descending fibres in CNS while schwann cells are responsible for myelination in PNS) 8. Phagocytes Formed in 2nd half of development from mesenchyme Form ependymal cell layer after neuroblasts and glioblasts formation is over 9. Present in T1-L3 segments of spinal cord