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21 Cards in this Set
- Front
- Back
DV axis formation |
Little is known ICM placement depends on sperm entry Ventral side hypoblast Dorsal is close to trophoblast |
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AP axis formation |
Based on implantation side Ectoderm is proximal, epiblast is distal DVE Distal visceral endoderm |
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AVE |
anterior visceral endoderm - extraembryonic structue BMP signals to induce wnt3 and nodal in epiblast |
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Node |
Equivilent to hensens node anterior end of primitive streak Embryonic Nodal signal induces expression of DVE |
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DVE induces AVE |
AVE promotes Wnt inhibitors - cerberus and dikkopf Nodal inhibitor lefty1 BMP inhibitors Prevents nodal activity in anterior FGF8 synthesized |
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Anterior |
No nodal BMP, Wnts, FGFs are inhibited No retinoic acid |
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Retinoic acid |
AP axis formation High in posterior Controls HOX genes |
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How many genes do mamals have HOX genes on? |
4 |
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HOX importance |
1. Specification of structures anterior to posterior 2. Paralogous groups (Hoxa-1, b-1, d-1) may be responsible for subsets of organs 3. Dominates over anterior - Posterior prevelence. Mutant means p dominates over a |
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Notochordal plate |
Deposited by node, mesanchymal cells move to anterior, stop at prechordal plate and form a plate, attached to endoderm, folds inward, rod, detaches from endoderm, end location is mesoderm |
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Functions of the notochord |
Induce neural tube
axis around which embryo develops axis to form vertebral column |
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Ectoderm to CNS and Epidermis |
Epidermis becomes the outer epithelial layer |
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Neural cells to neuroblasts |
1. Competence - exposed to right signals 2. Specification - received signal to become 3. Determination - will become neurons 4. Differentiation - neuroblasts |
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Neural plate |
First sign of a nervous system Ectoderm thickens from signals be mesoderm --> enlongated columnar neural plate cells Extends along ap axis, thinning as it goes |
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Neurulation |
Neural plate forms neural tube Neurula - embryo while this occurs Primary/secondary |
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Primary neurulation |
1. Shaping and folding of neural plate 2. Elevation of folds 3. Folds bend to form neural groove, convergence 4. Closure, neural crest cells form, zipper/ several sites MHP medial hinge point, DLHP |
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Expression of N and E cadherin |
Neural tube detaches due to switch in cadherin E - N Reduces binding affinity |
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Neural tube closure |
B12 important Not sure May be effected by vitimin intake, area, season, fungal infections, pesticides |
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Human neural tube closure, defects |
five locations Spina bifida - posterior failure or rupture Anencephaly - anterior Caniorachischisis - entire doesn't close |
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Sites 1-5 |
1. Rhombencephalon - spinal junction 2. Prosencephalon - mesencephalon 3. Rostral 4. Caudal 5. L2 and S2 |
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Secondary neurulation |
Occurs in tail region Condensation of mesechymal cells medullary cord - mesenchymal to epithelial condensing and bending |