Peripheral Nervous System Flashcards
When does the development of the Peripheral Nervous System (PNS) start?
PNS development starts from week 4 of embryonic development
What is the neural crest and how does it form during neurulation?
- the neural crest is a transient population of cells.
- it forms at the neural plate border during neurulation.
What is the origin of the PNS?
- PNS is derived from neural crest cells located between the neural tube and ectoderm.
- BMPs and Wnt signals from the ectoderm induce neural plate folding and neural crest cell formation.
What is neurulation?
Neurulation is the process of folding that leads to the formation of the neural tube.
What forms neural crest cells during neurulation?
The neural plate border (B) gives rise to neural crest cells during neurulation
What induces neural plate folding and neural crest cell formation?
BMPs (Bone Morphogenetic Proteins) and Wnt signals from the ectoderm induce both neural plate folding (to form the neural tube) & neural crest cell formation
what is delamination in NC cell migration?
- the process by which NC cells migrate from epithelia to mesenchyme during early development
- Cellular changes mediated by NC specifiers, such as Snail and foxD3, are involved in this migration
what mediates the cellular changes in NC cell migration?
- NC specifiers, such as Snail and foxD3, mediate the cellular changes involved in NC cell migration
What are the ventral and dorsal pathways in NC cell migration?
NC cells migrate through different pathways, ventral and dorsal, which lead to different fates for these cells
How are NC cells organized during migration by somites?
- NC cells migrate out of the anterior half of the somite, while the posterior half inhibits their migration.
- Inhibitory molecules in the posterior half include ephrin-B1/2 and sema3a.
- NC cells express Eph receptors, allowing them to avoid ephrin signaling and migrate effectively.
What is the role of segmental migration of NC cells in PNS organization?
- Segmental migration of NC cells contributes to the organization of the Peripheral Nervous System (PNS).
- NC cell dorsal root ganglia sit on either side of the spinal cord.
What are the roles of Wnt1 and BMP2 in neuronal differentiation?
Wnt1 promotes the differentiation of sensory neurons.
BMP2 promotes the differentiation of autonomic neurons.
Where do sympathetic neurons stop during migration, and what do they form when cultured?
- Sympathetic neurons stop close to the dorsal aorta during migration.
- When cultured, they form adrenergic (sympathetic) neurons.
- This differentiation is mediated by BMPs, initiating MASH1 and Phoxb2 cascades required for differentiation.
What is the Enteric Nervous System (ENS) and where do its cells come from?
- The Enteric Nervous System (ENS) is a part of the autonomic nervous system that controls the gut.
- ENS cells mainly come from NC cells from the vagal and sacral levels of the neural tube.
What is the role of Ret in ENS development?
- Ret is a transmembrane receptor tyrosine kinase.
- It acts with co-receptor GFRa1, with the ligand GDNF, to mediate ENS development.
- Mutations in Ret lead to defective peristalsis and no myenteric/submucous plexus due to the lack of NC cell migration.
- In GDNF + GFRa1 mutant mice, ENS development fails post to the esophagus.
