Neurulation And Neural Crest Cells Flashcards
In what week does Gastrulation take place?
Week 3
Describe the formation of the neural tube
- Notochord releases Shh
- Shh induces neural plate to begin to fold in and form neural groove.
- Neural groove keeps folding in, makes neural fold.
- Cells that join the neural fold to the surface ectoderm are neural crest cells
- Neural tube fully closes, neural crest cells become own entity
- Neural crest cells separate and migrate away from surface ectoderm
Difference between primary Neurulation and secondary Neurulation
Primary»DAY 25- closure of brain, cervical, thoracic, and lumbar (rostral pore)
Secondary»DAY 28- closure of sacral and coccyx (caudal pore). Caudal eminence fuses with posterior neuropore
Neural crest cells give rise to many things, what are they?
- sensory neurons
- neurilemma»Schwann cells
- leptomeninges»pita mater, arachnoid
- pigment cells
- c-cell of thyroid, chromaffin cells of suprarenal medulla
- bone and cartilage of the face
- wall of large arteries from aortic arches
- enamel and dentin
Hirschprung’s disease
- issue with trunk neural crest migration
- megacolon, cant poop
Congenital neural tube defects
What causes it and what are they? (4)
Failure of caudoneuropore to close at the appropriate time.
- Spinal bifida occulta
- Meningocele
- Meningomyelocele
- Myelocele (myeloschisis)
Spinal bifida occulta
- un fused vertebral arch
- 10% of people have this
- normal patient
- tuft of hair
- L5/S1
Meningocele
- Meninges cyst filled with CSF
- spinal cord is not displaced
- dura mater closed, but timing off
- patients may or may not have deficits
- elevated alpha fetal protein
Meningomyleocele
- Spinal cord displaced in CSF filled sac in dura mater
- patients do have deficits
- elevated alpha fetal protein
Myelocele
- spinal cord open and exposed
- patients have deficits
- need surgical correction
- elevated alpha-fetal protein
Cranial neural tube defects
What is the cause, and what are they? (3)
Rostral neuropore closing at inappropriate time
- Anencephaly- incompatible with life, missing neocortex and some skull
- Encephalocele with brain tissue-cyst like structure containing a varying amount of brain tissue, can cause mental and physical defecits
- Encephalocele without brain tissue-just cosmetic, i think. No defecits.
What is the meninix primitiva
- mesodermal in origin
- derived from scleratome
- becomes 2 things
1. Pachymeninx—which becomes the dura mater
2. Leptomeninges—which becomes arachnoid and pia mater
When does the embryo begin to fold?
Week 4
