6.02 Spina bifida, hydrocephalus, epilepsy Flashcards
What is the first important day in CNS development?
Day 18
Ectoderm thickens to form neural plate. It starts to invaginate to form the neural groove
What is the process of neural tube development called?
Neurulation
What are the 3 layers of the embryo?
Ectoderm, mesoderm, endoderm
When does the cranial neuropore close?
Day 24
Neuropore
The cranial and caudal openings before they fuse
Primary neurulation
Folding down to S2
Secondary neurulation
From S2 to coccyx. Neural tissue extends from the closed neural tube as a solid cord. The neural tube cavity grows into the structure.
Neural tube defects are caused by …
defective closure of the neural tube at the neuropores
Anencephaly
Failure of closure of the cranial neuropore. Skull fails to develop over the brain tissue. Exposed tissue degenerates and child born with most brain missing at birth
Once the neural tube closes, what happens to the cells?
Cell division, proliferation and migration. This happens in the cells closest to the lumen and they migrate “inside out”
When does cell division occur?
Weeks 7-16.
What happens during migration in the cortex?
The radial glia (scaffolding cells) form first and migrate out. Each new cell formed migrates past the existing cells via the radial glia. (“Inside out” formation)
Notochord
Made of mesoderm. Secretes SHH and initiates the formation of the neural plate
Types of spina bifida
Spina bifida occulta, spina bifida cystica meningocele, spina bifida cystica myelomeningocele
When is most brain neuronal proliferation complete?
By 16 weeks
