development of the nervous system: overview
DESCRIPTION
Development of the Nervous System: Overview. "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. What is an “organizer?”. ~19 days. - PowerPoint PPT PresentationTRANSCRIPT
Developmentof the
Nervous System:Overview
"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 3rd week of gestationin humans
What is an “organizer?”
~19 days
~23 days
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.
Ventricular layer = ependymal layer = proliferative zonebirthplace of CNS cells
Mantle layer = newly born, post-proliferative cellsMarginal zone = axonal layer
weeks3-4
weeks5-6
somites
Segmental/Genomic Models
Conventional Model
cervical flexure
cephalic flexure
Embryonic stages: conception to 8 wks
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 Imagesby
System
University of New South WalesEmbryology Online
http://www.rockefeller.edu/labheads/hatten/mechanism.html
Thanks to Aron Workman for finding this video clip.
Scanning EMof
Migrating Neurons
synapse withdrawal
axon retraction
programmed cell death(apoptosis)
Regressive Events in the Development of the
Nervous System
http://www.sumanasinc.com/webcontent/animations/content/neuronal_development.html
Animationof
Neuronal Proliferationand
Migration in the CNS