Weeks 3-6 Development 9/6
1. formation of the notochord: occurs around the 17th-18th day
cells that invade into the primitive node region and migrate along the median line cranially or rostrally form the
notochordal process
2. what does the notochord do: provides signals necessary for development of axial musculoskeletal
structures in CNS
3. what does notochord turn into: contributes to nucleus pulposus of intervertebral disc
4. how does notochord grow: as primitive node cells are added to proximal end
5. process of going from notochordal process to notochord: ventral floor of chord fuses
with endoderm and leaves behind flattened notochordal plate
plate detaches from endoderm
ends fuse together
6. neurulation: longest process
early CNS begins as simple neural plate that folds to form a groove then a tube that is open initially on both sides
7. neural tube defects: failure to close the openings of neural tube
1/2
, 8. where does neurulation occur: ectoderm via notochordal induction
9. first event of neurulation: around day 18 when neural plate thickens
10. neural plate: thickened ectoderm along midline
11. neural groove: shallow median groove of the neural plate between the neural folds
12. neural folds: the lateral longitudinal fold on each side of the neural plate ; first sign of brain development
13. neural tube: formed by fusion of the neural folds. precursor to the brain and spinal cords
14. neural crest cells: arise from the lateral lips of the neural plate and detach during formation of the neural
tube; form a variety of structures
15. neural tube closure: involves adhesion of neural folds
begins on day 22 at future occipital and cervical regions
16. which way does neural tube close: both cranial and caudal directions
17. clinical cases of neural tube defects: anencephaly and spina bifida
2/2
1. formation of the notochord: occurs around the 17th-18th day
cells that invade into the primitive node region and migrate along the median line cranially or rostrally form the
notochordal process
2. what does the notochord do: provides signals necessary for development of axial musculoskeletal
structures in CNS
3. what does notochord turn into: contributes to nucleus pulposus of intervertebral disc
4. how does notochord grow: as primitive node cells are added to proximal end
5. process of going from notochordal process to notochord: ventral floor of chord fuses
with endoderm and leaves behind flattened notochordal plate
plate detaches from endoderm
ends fuse together
6. neurulation: longest process
early CNS begins as simple neural plate that folds to form a groove then a tube that is open initially on both sides
7. neural tube defects: failure to close the openings of neural tube
1/2
, 8. where does neurulation occur: ectoderm via notochordal induction
9. first event of neurulation: around day 18 when neural plate thickens
10. neural plate: thickened ectoderm along midline
11. neural groove: shallow median groove of the neural plate between the neural folds
12. neural folds: the lateral longitudinal fold on each side of the neural plate ; first sign of brain development
13. neural tube: formed by fusion of the neural folds. precursor to the brain and spinal cords
14. neural crest cells: arise from the lateral lips of the neural plate and detach during formation of the neural
tube; form a variety of structures
15. neural tube closure: involves adhesion of neural folds
begins on day 22 at future occipital and cervical regions
16. which way does neural tube close: both cranial and caudal directions
17. clinical cases of neural tube defects: anencephaly and spina bifida
2/2
