1. Development of the Nervous System: Overview

2. "It is not birth, marriage, or death, but gastrulation, which is truly the most important time in your life." Lewis Wolpert (1986) Gastrulation occurs during 3 rd week of gestationin humans

4. What is an “organizer?”

5. ~19 days ~23 days

15. Rules for the Birth of Cells in the CNS 3. Motoneurons are born before sensory neurons. 2. Large neurons are born first. 5. Glia proliferate after neurons, with the exception of radial glia. 4. Interneurons last of neurons born. 1. Proliferation begins in cervical segments and proceeds rostrally and caudally from there.

16. Ventricular layer = ependymal layer = proliferative zone birthplace of CNS cells Mantle layer = newly born, post-proliferative cells Marginal zone = axonal layer

21. weeks 3-4 weeks 5-6 somites

23. Segmental/Genomic Models Conventional Model

26. cervical flexure cephalic flexure

29. Embryonic stages: conception to 8 wks

30. http://www.med.unc.edu/embryo_images/ unit-nervous/nerv_htms/nervtoc.htm http://php.med.unsw.edu.au/embryology/ index.php?title=Main_Page Embyronic Images by System University of New South Wales Embryology Online

33. http://www.rockefeller.edu/lab heads/hatten/mechanism.ht ml Thanks to Aron Workman for finding this video clip. Scanning EM of Migrating Neurons

34. synapse withdrawal axon retraction programmed cell death (apoptosis) Regressive Events in the Development of the Nervous System

35. http://www.sumanasinc.com/webcontent/animations/ content/neuronal_development.html Animation of Neuronal Proliferation and Migration in the CNS