Lecture 10 Flashcards
(25 cards)
What structures are made out of the surface ectoderm?
Anterior pituitary, lens, and cornea
What structures are made out of the neural tube?
posterior pituitary, retina, optic nerve, brain, spinal cord
What structures are made out of the neural crest cells?
adrenal medulla, autonomic and sensory nerves
What happens during the 3rd week of development?
Notochord induces the cells of the overlying ectoderm to differentiate into neuroectoderm
Neuroectoderm contains neural plate and neural groove
Neural tube makes up the CNS
The neural crest cells make up the PNS and ANS
When does neurulation occur?
On the 22nd day at the occipital and cervical region
What are the two initial zones of spinal cord development?
The marginal zone and the ventricular zone
What does the ventricular zone give rise too?
ventricular zone = give rise to neurons and microglia in the spinal cord
What do the cells in the ventricular zone called when they multiply and form new cells?
The intermediate layer
these cells will eventually form neurons
What does the intermediate zone form?
pair of alar plates (dorsal horns and dorsal gray columns)
pair of basal plates (ventral somatic motor and lateral horns)
What separates the alar and basal bodies?
sulcus limitans
gray matter vs white matter?
intermediate zone forms gray matter
marginal layer forms the white matter
Where do microglial cells derived from?
mesenchyme
What are neurons and most support cells derived from?
neuroepithelium
When does myelination start?
late during fetal development through the first year of life
How are the vertebra develop?
mesenchyme of the pair of sclerotomes which surround the neural tube and the notochord at each level
What are the two regions of the sclerotome?
Caudally placed, densely packed cells→ forms intervertebral disc and part of vertebral body
Cranially placed, loosely packed cells→ forms vertebral body together with rest of dense tissue
What region of the sclerotome is the spine formed from
Intervertebral disc develops from the caudal dense part of the Sclerotome
It forms the anulus fibrosus of the disc
What are the ossification centers on the vertebra and when do they develop?
- the body (5th and 6th weeks)
2. two neural arch centers (7th week)
Explain chordoma?
The notochord in the region between developing vertebral bodies persists and forms the nucleus pulposus
It is a slow growing, rare malignant tumor when remnants of the notocord remain
may spread to the bones, but most frequently at the base of the skull.
spina bifida occulta?
- no bulge over the bony defect
- no neurological impacts
- a tuft of hair or dimples may be present
lumbosacral region
spina bifida (cystica with meningocele)?
- Bulge is seen over the defect
- Contains meninges & CSF in the subarachnoid space
neurological defects are uncommon
lumbar presentation is most common
spina bifida (cystica with meningomyelocele)
- Bulge is seen over the defect
- Contains meninges, cord & nerves
Severe neurological deficits are common ranging from paralysis, sensory loss, bladder dysfunction.
spina bifida (cystica with myeloschisis)
Skin and bony defect with “open” spinal cord, seen as a mass of neural tissue
meroencephaly?
failure of rostral neuropore to close
absence of a large part of the brain and skull
usually lethal
exact cause is not known
