Flashcards in Neural Crest Deck (34)
What induces neural crest into non-neuronal ectoderm?
-BMPs and Wnts
-inhibitory actions of noggin and chordin
What induces neural crest from mesoderm?
While in the neural tube, neural crest cells are what? What helps form tight junctions?
-cadherins and other CAMs are important in forming tight junctions
What are the factors involved in neural crest breaking free?
-CAMs are lost and remain downregulated during migration but may be reexpressed at the end of migration
-Snail -1, Snail-2, and Foxd3 are important in allowing cells to break free
What are the three migratory pathways of neural crest migration?
-ventral/sympathoadrenal path: first emigrating cells
-ventrolateral path: second wave of emigrating cells
-dorsolateral path: last wave of emigrating cells
What are the migratory neural crest substrates? Ligand/receptors?
-basal lamina is preferable
-extracellular matrix components
+type IV collagen
-ligand/receptor pair guidance molecules
Early migratory neural crest cells:
-have most potential for differentiation
Later migratory neural crest cells:
-can only differentiate into cells characteristic of more dorsal locations
Late migratory neural crest cells:
-can only form melanoblasts
What are the neural crest cell divisions?
-trunk neural crest
-cranial neural crest
-circumpharyngeal neural crest
-cardiac neural crest
Neural crest pathways extend from where?
-somite 6 caudally
Outline the sympathoadrenal pathway.
-follows intersomitic blood vessels around and between somites
Outline the ventrolateral pathway.
-neural crest cells enter and pass through anterior sclerotome compartments
+repulsed from posterior compartment by interaction of semaphorinA3F and neuropilin-2
+passage is facilitated via thrombospondin
Outline the dorsolateral pathway.
-migrate just beneath ectoderm
What happens to neural crest cells that take the sympathoadrenal lineage?
-gives rise to:
+adrenal chromatin cells
+adrenergic sympathetic neurons
+cholinergic sympathetic neurons
What happens to neural crest from the sensory/ventrolateral lineage?
-dorsal root ganglia
What happens to neural crest from the melanocyte/dorsolateral lineage?
Cranial neural crest are thought to have been involved in evolution of what? Where do they arise from?
-cells arise from region of prosomere 1-3 and migrate as a continuous sheet over much of the head
What inhibits neural crest cells from arising anterior to diencephalon?
Cells arising from diencephalon posteriorly through R3 do not express what?
Cells from R4 and posteriorly DO express what?
Neural crest cells from R1-R2 -> pharyngeal arch 1
- does not require Hox influence
Neural crest cells from R4 -> pharyngeal arch 2
-requires Hoxa2 to keep it from becoming first arch
Neural crest cells from R6-R7 -> pharyngeal arch 3
Where does circumpharyngeal neural crest arise from?
-areas of somites 1-7
What does the circumpharyngeal ridge do?
-arc shaped aggregation of cells passing behind 6th arch
-cells migrate centrally and then cranially to provide pathways for CN XII and related musculature
-most neural crest cells from somites 1-3 -> pass into pharyngeal arches 4 and 6 or form cardiac crest
-neural crest cells from R4-7 -> make up vagal crest and form parasympathetic innervation for digestive tract
Where does cardiac neural crest arise from?
Cardiac neural crest migrate toward the heart and give rise to what?
-septa that divide conus arteriosus into aortic and pulmonary arteries
-leaflets of semilunar valves
-thymus, thyroid, parathyroid glands
Where does vagal neural crest come from?
-arises from circumpharyngeal crest and exit from levels of somites 1-7