Lecture 19 Flashcards
neural crest cells originate from the lateral margins of the what?
neural plate
the induction of neural crest tissue from the non-neural ectoderm uses what genes?
BMPs and Wnts
induction of neural crest tissue from mesoderm involves what gene?
FGF-8
what 3 genes are important in allowing cells to break free?
Snail-1, snail-2 and Foxd3
in neural crest cell migration, the ventral/sympathoadrenal pathway has what wave of emigrating cells?
first wave
in neural crest cell migration, the ventrolateral pathway has what wave of emigrating cells?
second wave
in neural crest cell migration, the dorsolateral pathway has what wave of emigrating cells?
last wave of cells
early migratory neural cells have most potential for differentiation. later cells have more dorsal locations. the latest cels can only form what?
melanoblasts
neural crest cells divide into 5 different crests
trunk, cranial, circumpharyngeal, cardiac and vagal
the trunk neural crest contains 3 migration pathways
sympathoadrenal, ventrolateral, dorsolateral
trunk neural crest contains 3 lineages
sympathoadrenal, sensory and melanocyte
the cranial neural crest is thought to have been involved in the evolution of what?
vertebrate head
neural crest cells from R1-R2 give rise to pharyngeal arch 1 and do not require what genes
Hox
neural crest cells from R14 give rise to pharyngeal arch 2 and requires what gene
Hoxa2
neural crest cells from R6-R7 give rise to pharyngeal arch 3 and requires what gene
Hox3
circumpharyngeal neural crest arises from area of what somites
1-7
most neural crest cells from somites level 1-3 pass into the pharyngeal arches 4 and 6 and form the
cardiac crest
neural cells from somite levels 1-3 and 4-7 make up the
vagal crest
this gene prevents neurons from crossing the midline of the central nervous system
Slit-2
this gene works to avoid cells the express slit-2. vagal crest cells do not express this and are able to cross the gut wall.
Robo (slit receptor)
this syndrome involves pax-3 mutations and involves white stripe in the hair, deafness, cleft palate ect.
waardenburgs
this condition is characterized by a deficiency in migration of neural crest cells into pharyngeal arches, mesoderm formation
charge
this neurocristopoathy is due to a deletion in chr 22, and is related to defects in neural crest associated with 3rd and 4th pharyngeal arches, also called Q22
DiGeorge syndrome
local thickening in embryonic ectodermal layer that generally makes up a group of cells in which an organ or ganglion will form
ectodermal placodes
there are 6 major ectodermal placodes
hypophyseal, olfactory, lens, trigeminal, otic, and epibranchial
the initial expression of this gene is in the lens, nasal placodes and diencephalon. absence of this gene results in early optic vesicle formation, but the rest of the eye does not develop.
Pax6
low concentrations of Shh in distal optic stalk permits expression of Pax6 and development of optic vesicle, this will lead to the formation of what?
retina
high concentrations of Shh in the proximal optic stalk decreases the expression of Pax6 and induces the expression of what?
Pax2
what gene is necessary for corneal induction?
Pax6
what gene is necessary for the differentiation of the pigmented retina and is stimulated by Shh?
Otx2
the nasotemporal (a/p) axis is fixed first and established in part by what gradients?
ephrins and receptors
the dorsoventral axis is fixed second and is established by what gradients?
by the antagonist actions of Shh, BMP, ventropin, Tbx5, Pax2, Vax2
