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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

AP axis formation

Based on implantation side

Ectoderm is proximal, epiblast is distal

DVE Distal visceral endoderm


anterior visceral endoderm - extraembryonic structue

BMP signals to induce wnt3 and nodal in epiblast


Equivilent to hensens node

anterior end of primitive streak


Nodal signal induces expression of DVE

DVE induces AVE

AVE promotes Wnt inhibitors - cerberus and dikkopf

Nodal inhibitor lefty1

BMP inhibitors

Prevents nodal activity in anterior

FGF8 synthesized


No nodal

BMP, Wnts, FGFs are inhibited

No retinoic acid

Retinoic acid

AP axis formation

High in posterior

Controls HOX genes

How many genes do mamals have HOX genes on?


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

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

Functions of the notochord

Induce neural tube

axis around which embryo develops

axis to form vertebral column

Ectoderm to CNS and Epidermis

Epidermis becomes the outer epithelial layer

Neural cells to neuroblasts

1. Competence - exposed to right signals

2. Specification - received signal to become

3. Determination - will become neurons

4. Differentiation - neuroblasts

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


Neural plate forms neural tube

Neurula - embryo while this occurs


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

Expression of N and E cadherin

Neural tube detaches due to switch in cadherin

E - N

Reduces binding affinity

Neural tube closure

B12 important

Not sure

May be effected by vitimin intake, area, season, fungal infections, pesticides

Human neural tube closure, defects

five locations

Spina bifida - posterior failure or rupture

Anencephaly - anterior

Caniorachischisis - entire doesn't close

Sites 1-5

1. Rhombencephalon - spinal junction

2. Prosencephalon - mesencephalon

3. Rostral

4. Caudal

5. L2 and S2

Secondary neurulation

Occurs in tail region

Condensation of mesechymal cells

medullary cord - mesenchymal to epithelial

condensing and bending