Development of the nervous system Flashcards
What is gastrulation?
Formation of a three-layered embryo from previous two layered (hypoblast and epiblast)
What germ layer does the brain develop from?
Ectoderm (along with skin)
What is the first well-defined neural tissue to form, and when does this happen?
The neural tube (days 20-27)
What constitutes the a) embryonic and b) foetal periods?
a) conception to nine weeks
b) week 9 to term
What does the term “lissencephalic” mean?
Brain which is smooth in contour
Describe the division and migration of neural progenitor cells.
Divide asymmetrically to give a post-mitotic neurone and another NPC
Neurones migrate to take their place in the neocortex- six-layered structure in “reverse” order with the first to migrate closest to the centre
What proportion of neurones undergo prenatal apoptosis?
50%
What are the three main methods of neuronal migration?
Somal translocation
Radial glial guides
Tangential migration
Postnatally, where does the only proliferation and migration continue to take place?
Olfactory bulb, gentate gyrus and glial progenitors
Which cells are responsible for myelination in the CNS?
Oligodendrocytes
What is spinda bifida an example of?
Neural tube defect
What is holoprosencephaly?
Failure of brain vesicles to form properly
What is Pelizaeus-Merzbacher disease an example of?
Disorder of myelination causes PLP-1 mutations
