Development of the CNS

Question 1

Development of the Brain

Answer 1

1. Proliferation: new cells produced inside the neural tube when embryo is 2.5 weeks old
2. Migration: Immature neurons migrate to their final destination in the brain beginning at about 8 weeks.
   
   1. once there, they aggregate with other cells to form the structures of the brain.
3. Differentiation: neurons initially look very much like other cells of the body but following migration, develop Axons and Dendrites!
4. Myelination: axons of some neurons myelinate, when glial cells form an insulating sheath around the cell’s axon. Most occurs postnatally.
5. **Synaptogenesis: **timing of formation of synapses depends on the specific area of the brain, but most occurs postnatally.
   
   1. influenced by both endogenous (genetic) and exogenous (experience) factors.

neurons are initially over-produced, and many undergo an active pruning during prenatal development and for several years following birth.

Apoptosis: cell death (pruning) apparently to fine-tune brain development.