At approximately day 1

Neuroectoderm arises from ectoderm by the end of week 3.

Duration: 1 week

Reference

Evans OB, Hutchins JB. 1997. Development of the Nervous System. Chapter 5 In: Haines DE, ed. Fundamental Neuroscience. New York: Churchill Livingstone.

At approximately day 1

Mesenchymal cells begin to migrate and notochord formation begins.

Reference

Moore KL, Persaud TVN. 1998. The Developing Human: Clinically Oriented Embryology. 6th ed. Philadelphia: WB Saunders Co.

At approximately day 3

Neural plate develops

Reference

Moore KL, Persaud TVN. 1998. The Developing Human: Clinically Oriented Embryology. 6th ed. Philadelphia: WB Saunders Co.

At approximately day 4

Neurogenesis of spinal cord, medulla and pons, through week 7.4.

Duration: 4 weeks

Reference [PubMed Link]

Bayer SA, Altman J, Russo RJ, Zhang X. 1993. Timetables of neurogenesis in the human brain based on experimentally determined patterns in the rat. Neurotoxicology 14(1):83-144.

At approximately day 5

Neural groove and primitive node are visible; somites begin to appear.

Reference

Moore KL, Persaud TVN. 1998. The Developing Human: Clinically Oriented Embryology. 6th ed. Philadelphia: WB Saunders Co.

At approximately day 6

Neural folds develop from neural plate thickening at the lateral margins.

Reference

Evans OB, Hutchins JB. 1997. Development of the Nervous System. Chapter 5 In: Haines DE, ed. Fundamental Neuroscience. New York: Churchill Livingstone.

At approximately day 7

Most of the neural plate infolds and fuses (primary neurulation) to form neural tube; gives rise to brain and spinal cord through lumbar segment. Neuroblasts (immature future neurons) divide and change morphology during neurulation to form neural tube.

Duration: 1 week

Reference

Evans OB, Hutchins JB. 1997. Development of the Nervous System. Chapter 5 In: Haines DE, ed. Fundamental Neuroscience. New York: Churchill Livingstone.

At approximately day 7

The sacral and coccygeal segments of the spinal cord are formed from the caudal eminence (secondary neurulation)

Duration: 4 weeks

Reference

Evans OB, Hutchins JB. 1997. Development of the Nervous System. Chapter 5 In: Haines DE, ed. Fundamental Neuroscience. New York: Churchill Livingstone.

At approximately day 7

During neurulation, neural crest cells (located in neural tube) detach and migrate to spinal cord and brain and give rise to peripheral nervous system and other tissues.

Duration: 2 weeks

Reference

Larsen WJ. 1997. Human Embryology. New York: Churchill Livingstone Inc.