Lec 11 Overview of CNS Development Flashcards
What are the two exceptions to the rule that entire nervous system develops from the ectoderm?
- microglia and dural mater
- both develop from mesoderm
What is gastrulation?
- induction of neural ectoderm from general ectoderm
- forms neural plate
What are the steps of CNS development?
- gastrulation [formation neural plate]
- neurulation [formation of neural tube]
- histogenesis [3 tissue layer formation]
- end neurulation [closure neural tube]
- vesicle formation
When does gastrulation happen in embryo growth?
at approximately 16 days
What is neurulation?
- development of neural tube and neural crests from neural ectoderm
What are the steps in neurulation?
- cell proliferation at margins of neural plate, created neural groove between neural folds
- cells lining groove give rise to cells of CNS
- margins of neural folds grow toward each other and fuse in midline to form neural tube
What do neural crest cells become?
PNS
- sensory ganglia of cranial and spinal nerves
- spinal sensory + motor nerves
- ANS [parasymathetic, sympathetic, enteric nervous systems]
- schwann cells
- leptomeninges [pia + arachnoid]
What does the cavity of the neural tube become?
the ventricular system
When does neural tube closure begin? finish? Does anterior or posterior end of neural tube close first?
begins ~22 days, done anterior first (26 days) then posterior (28 days)
When does neurulation start?
~ 20 days
What marks cephalic closure of the neural tube?
lamina terminalis
What does neural tube become?
CNS
- brain [cerebrum and brainstem]
- spinal cord
What is histogenesis?
- formation of 3 layered tube consisting of
1. internal ependymal layer
2. middle layer of mantle cells that will become gray matter
3. external layer that will become white matter
neurons develop from neuroblasts and migrate into the middle mantle layer
What is the lamina terminalis? Its fate?
- marks the closure of the cephalic end of neural tube
- becomes the anterior wall of 3rd ventricle
What are the 3 cephalic vesicles formed after neural tube closure?
- forebrain [prosencephalon]
- midbrain [mesencephalon]
- hindbrain [rhombencephalon]
When does neural tube formation occur in development [in wks]?
3-4 wks