Lecture 6: Development of CNS Flashcards
When does fertilization occur?
When sperm meets oocyte forming zygote
What is the cell division process?
Zygote become morula (16 cells) which then becomes a blastula
What begins after formation of a blastula?
Gastrulation begins
What is the blastopore?
Initial site of invagination
What does the invagination of a single sheet of cells produce?
3 germ layers: ectoderm, mesoderm, endoderm
What is defined in gastrulation?
Spatial orientation of the embryo
What is the notocord formed as?
A cylinder of mesodermal cells defining midline
What does the notocord formation signal?
The overlying ectoderm to become neuroectoderm
What is the CNS derived from?
Neuroectoderm
What happens to the neuroectoderm as development progresses?
It invaginates
What happens to lateral margins?
Also known as neural folds, they fuse along midline forming neural tube, and internally, the neural canal
What is at the junction of the ectoderm and neuroectoderm?
A layer of ectodermal epithelial cells (neural crest cells) that separates as the neural tube is formed
Where does initial closure begin? Where does it progress?
Begins at rhombencephalon and progresses rostrally and caudally
What may persist after closure?
A small opening may persist caudally maintaining communication of the subarachnoid space with conus medullaris
What 3 vesicles develop during closure?
Prosencephlaon
Mesencephalon
Rhombencephalon
What does the prosencephalon form?
Cerebral hemispheres (which contain telencephalon vesicles) Diencephalon, which is the rostral aspect of the neural tube (contains optic vesicles)
What does the notochord secrete?
Sonic Hedge hog
What does sonic hedge hog do?
Stimulates motor neuron development
What cell layer does the neural tube develop from?
Ectoderm/neuroectoderm
What are the 4 neurologic features that develop from the neural crest cells?
Dorsal root ganglia
Post ganglionic neurons of ANS
Leptomeninges
Schwann cells
What are the 3 vesicles that form the brain?
Prosencephalon
Mesencephalon
Rhombencephalon
What does the prosencephalon form?
Telencephalon (cerebrum)
What does the mesencephalon form?
Mesencephalon (midbrain)
What does the rhombencephalon form?
Metencephalon (pons and cerebellum)
Myelencephalon (medulla)
What is found in the germinal layer?
Ependymal cells
What is found in the mantle layers?
Gray matter
Where is gray matter located in the spinal cord?
Central to the white matter
Where is gray matter located in the cerebral cortex and cerebellum?
Peripheral to the white matter
What is found in the marginal layer?
White matter
