Neuralation Flashcards
1
Q
What structures form that become the neural tube and how?
And when is neural tube formation complete?
A
- Neural Plate (AKA neuroectoderm) - notochord induces ectoderm to thicken (cranial to prim. node > OP membrane) into this via TGFB
- **Neural Groove **forms via invagination of plate
- Neural Folds on either side of groove stick up, more prominent at cranial end
- the folds move together and fuse over the groove to form the neural tube by the end of week 3
2
Q
Describe the formation of the neural crest and what it becomes within the mesoderm.
A
- Crests of each neural fold de-epithelialize (EMT?) and detach
- These neural crest cells migrate to form flattened mass, the neural crest, over the neural tube
- The neural crest then splits in two and migrates to either side of the neural tube to form the primordia of the sensory ganglia of cranial/spinal nerves
3
Q
What are some of the derivatives of neural crest cells?
A
- dorsal root ganglia
- CN V, VII, IX, X ganglia
- peripheral neurilemmae
- meninges
- pigment cells
- adrenal medulla
- skeletal/muscle components of head
D C N M P A H
4
Q
What is secondary neuralation?
A
neuroectoderm and endoderm form the conus medullaris
- cone shaped end of spinal cord just above the cauda equina
5
Q
What 5 things form in the cranial ectoderm as the neural tube closes?
What do they become?
A
Placodes
- symmetrical thickenings of ectoderm
- OL HOT
- Otic - epi cells of hearing, vestibular apparatus, assoc. ganglia
- **Lens **- eye lens
- **Hypophysis **- Rathke pouch > adenohyphophysis
- **Olfactory **- olfactory epi. + GNRH secretors
- **Trigeminal **- neurons + glia of trigem ganglion
6
Q
What are the openings at either end of the embryo formed during neural tube formation?
When do they close?
A
neuropores
cranial - day 25
caudal - day 27
7
Q
What morphogenetic factors induce some of neuralation?
Via what genes?
A
retinol
Wnt gene products
induce Homeobox (HOX) genes
8
Q
A
