BMS1052 Developmental Neurobiology – lecture 2 Flashcards
Neural crest development
• The border region between the neural plate and ectoderm is induced to become neural crest.
- some signals similar to the neural tube some are different due to different location
- Neural crest cells express different genes to the neural plate/neural tube to different target sites
how do the crest cell separate from neural tube?
They undergo a process of epithelial mesenchymal transition to allow them to break free from the neural
tube and migrate to different target sites
The neural crest form
The neural crest form neurons and glia of the peripheral nervous system, and many other cell types
• Dorsal root ganglia
• Sympathetic and parasympathetic ganglia
• Enteric nervous system
Neural crest cells undergo an epithelial-mesenchymal
transition
• Epithelial to mesenchymal transition involves
changes in:
- cell adhesion- reduced cell adhesion
- polarity – epithelial cell has polarity, mesenchymal don’t
- Cell shape
- Cell-matrix adhesion- epithelial cell has adhesion to basal lamina
transition from epithelial cell to mesenchymal cell which has greater ability to
move
Neural crest migration in the trunk
• Following induction, neural crest cells migrate away from the neural tube.
• Neural crest cells follow various pathways to their target sites.
• Cells that will form the sympathetic ganglia migrate to
the dorsal aorta.
• Cells that will form the sympathetic ganglia migrate to
the dorsal aorta.
Neural crest cells in the trunk form:
Dorsal root ganglia Sympathetic ganglia Pigment cells Adrenal medulla neural crest cell the entire cell moves the neurons in the brain = axon migration cell body in the brain
Formation of sympathetic chain ganglia
- Neural crest migrate to the dorsal aorta.- major blood vessel in embryo
- Cells are dispersed along the
aorta (no segmentation). - Cells aggregate into discrete ganglia.- involved increase in cell adhesion - Cells aggregate together into ganglia (collections of cell bodies)
when they migrate cell-cell adhesion decreases
when the cell come together cell-cell adhesion increases
Sympathetic neuron development
Neurite outgrowth- axon guidance, guidance cues, cell-cell adhesion and blood vessels
• Axon growth and guidance to peripheral
targets
Sympathetic ganglia move to a more dorsal position
process controlled by signals and receptor produced by the sympathetic ganglion neurons
sympathetic ganglia drawn to the spinal cord
axons from the neurons in the spinal cord extends out and synapse onto the symp ganglia - secondary ganglia extends their axons out in the periphery
Preganglionic neurons in the spinal cord synapse on
neurons in one or more sympathetic ganglia (creating the chain)
Neurotransmitter plasticity
Most sympathetic ganglion neurons use noradrenaline as a neurotransmitter.
Some use acetylcholine.
Some neurons can change phenotype (eg from adrenergic to cholinergic).
as result of change in gene expression in those neurons and the target is the main factor mediating this. sending signal from the target organ
to the cell body mediating that change in neurotransmitter that is being used
happes in parasympatheic and CNS
Myelination and glia in the periphery
Schwann cells ( myelinating ) and Satellite cells (in ganglia ) develop from the neural crest.
Tumours from the peripheral nervous system
- Sympathetic ganglion cells can give rise to neuroblastoma
- It most commonly develops from neuroblasts in the adrenal medulla.
- It is the most common solid tumour in childhood.
Important discoveries have been made using a variety of models
Drosophila • discovery of critical axon guidance molecules C. elegans • Role of specific neurons • Axon regeneration
