Lecture 16- Neural crest II (migration and differentiation) Flashcards
What determines where neural crest cells migrate and what types of cells they form?
-the target sites and the cell types formed depend on the axial (rostrocaudal) level
What are the four divisions of the axial (rostrocaudal) level along the neural tube?
- Cranial
- Vagal
- Trunk
- Sacral
What are the 5 methods to study neural crest migration?
- Surgically remove defined regions of the neural crest, and then determine which structures fail to develop
- Construction of chick-quail chimeras
- Label pre-migratory cells with fluorescent dyes or radioactive substances
- Intrinsic markers of neural crest cells, including localization by immunohistochemistry or in situ hybridization
- Transgenic animals expressing reporter genes -Combinations of the above techniques can be used answer particular questions.
What are the advantages/disadvantages of method 1: Surgically remove defined regions of the neural crest, and then determine which structures fail to develop?
- Advantages: shows the importance of particular regions of neural crest
- Disadvantages: can’t see how the cells get there, or if other cells compensate for the loss of regions. Depends on high level of skill
- the first method used, cut out bits of the neural crest and see what doesn’t develop
What are the advantages/disadvantages of method 2: Construction of chick-quail chimeras?
Advantages: Can identify cells during migration (using fixed embryos). Cells are permanently identified.
Disadvantages:
- can’t imagine live cells during migration (using fixed embryos)
- Transplantations are difficult and somewhat variable.
- also look at sections of the embryos
- if you stop the embryo during development= so can see where they are
What are the advantages/disadvantages of method 3: Label pre-migratory cells with fluorescent dyes or radioactive substances?
- Advantages: Can image the cells in live embryos. Can label a variable number of cells (1 cell to hundreds or more). Can label different groups of cells or cells in precise locations (fate maps). Very useful for short- term labelling.
- Disadvantages:
- The labels are not permanent and are diluted out of the cells over time. -1970s -match with quail and chick chimeras
- can image cell in live embryos
more notes:
- can label in different colours and different groups of cells
- it is short term, dilute out of the cells over time as they divide, daughter cells have less and less with each division
What are the advantages/disadvantages of method 4: Intrinsic markers of neural crest cells, including localization by immunohistochemistry or in situ hybridization?
Advantages:
- Label specific genes or populations of neural crest.
- Can also use antibodies to other markers concurrently (eg look at proliferation or cell death).
- Can use to see how specific neural crest genes are affected following experimental manipulation.
Disadvantages:
-can only label fixed tissue (no live imaging).
What are the advantages/disadvantages of method 5: Transgenic animals expressing reporter genes?
Advantages:
- Can track cells using live imaging.
- Can permanently label cells using some approaches.
Disadvantages:
- Need to make/have the appropriate transgenic.
- Permanent transgenic more feasible in certain species (mice, zebrafish).
- Can make transient transgenic chick and Xenopus.
- the only live imaging and it is also permanent, hard to do
How do neural crest cells from different rostro-caudal levels migrate and what do they give rise to?
- Neural crest cells from different rostro-caudal levels:
- Follow different migratory pathways
- Give rise to different derivatives
Which neural crest cells migrate first?
-cranial region neural crest cells
Which neural crest cells migrate last?
-sacral region neural crest cells
In which order do the neural crest cells form and migrate?
- neural crest cells form and migrate in a rostrocaudal wave
- cranial, then vagal, then trunk, and lastly sacral region neural crest cells form and migrate
- this is due to the rostrocaudal wave in which the neural tube closes

What type of tissues do cranial neural crest cells give rise to?
- neurons and glia and cranial ganglia
- cartilage and bones
- connective tissue

What type of tissue do trunk crest neural cells give rise to?
- Pigment cells
- Sensory neurons and glia
- Sympatho adrenal cells

What type of cells do cranial neural crest cells give rise to?
- migrate first
- cranial sensory glia (together with placode cells)
- parasympathetic ganglia
- Schwann cells
- cartilage and bone
- smooth muscle
- connective tissue
- cornea
- teeth
- pigment cells (melanocytes)

What type of cells do vagal neural crest cells give rise to?
- cardiac outflow tract septum
- ventricular septum
- enteric neurons and glia

What type of cells do trunk neural crest cells give rise to?
- sympathetic ganglia
- dorsal root ganglia
- adrenal chromaffin cells
- schwann cells
- pigment cells

What type of cells do vagal neural crest cells give rise to?
- parasympathetic ganglia
- enteric neurons

Cranial neural crest, what does it form: details?
- form bone, cartilage and connective tissue in the head and neck
- the entire facial skeleton and much of the skull, including the upper and lower jaws, the palate and hyoid bone
- dermis, smooth muscle of the skin
- smooth muscles of blood vessels forming the aortic arch and the outflow tract of the heart (cardiac neural crest)
- connective components of striated muscle and glands in the head
- some endocrine cells, e.g parafollicular cells of the thyroid

Do placodes only produce neurons?
- yes
- glia are all from neural crest cells
What can happen if there are prblems on the development of cranial neural crest?
- can lead to caniofacial defect
- e.g. Treacher Collins syndrome: very rare, caused by a failure of the neural crest migrating to branchial arch 1 to survive (Tcof1 mutation), not enough of the migrating neural crest cells survive
- also cleft lip and palate:most common
- jaw malformation (micrognathia)
- these are not always due to neural crest cells problems but they can be involved
How are cranial ganglia formed?
- Cranial neural crest together with placodes form cranial ganglia.
- There are 2 sorts of cranial ganglia, sensory ganglia (associated with cranial nerves) and parasympathetic ganglia.
What can placodes give rise to?
-Placodes give rise to some neurons in sensory cranial ganglia and several other structures

What are placodes?
-specialised (thickened) regions of ectoderm
- develop from ectoderm
- induced by growth factors, different ones with different placodes
- get expression of genes, gets thicker
- two ways in which they develop=
- some invaginate (left) and
- on the right= undergo process of delamination (change from epithelial cell type and coming into the mesenchyme, don’t go very far, form a ganglion under the ectoderm
- Cells from the placodes enter the mesenchyme and combine with neural crest cells to make ganglia.
- Neurons in the cranial sensory ganglia arise from:
(a) placodes
(b) neural crest - Glia in the cranial ganglia arise from the neural crest.





