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Neurulation in
the chick,
after the node
regresses
Typical vertebrate organization of the chick embryo
(and >200 selector gene domains)
“Somatic mesoderm”
“Visceral mesoderm”
Notochord
**Or wait until the
embryo lifts
off the yolk sac
Extra-embryonic membranes of the chick
Amnion and chorion: contain ectoderm and
somatic mesoderm
Yolk sac and allantois: contain enododerm and
visceral mesoderm
Chick development: Formation of the allantois
Human or mouse embryo: pre-implantation stages
2. 2Blastocyst cavity formation
3. Cell sorting (hypo vs. epi)
4. hatching
128 cell
Day 7-human
Day 5.5-mouse
1. compaction
gene expression starts
128-cell blastocyst
compaction
128-cell blastocyst
Mouse pre-implantation stages:
compaction, apical-basal polarization,
cleavage, blastocyst cavity formation
Compaction at the late 8-cell stage,
With apical-basal polarization of cells
Human 128cell blastocyst before/during hatching
Oct4 gene expression in epiblast
“zona”
Holding pipet
Injection pipet
Injection of
ES cells into the
blastocyst cavity
Mouse embryonic stem cells (ES cells)
from the inner cell mass, growing in a culture dish
Dr. Mario
Capecchi-1984
Univ. of Utah
(random)
(e.g., GFP
with promoter)
Mouse transgenesis (insertion of a
foreign gene into the mouse genome)
non-homologous integration
FOSTER
MOTHER
(2x)
Green ES cells
Gene for red fluorescent
protein (RFP)
Gene for green fluorescent
protein (GFP) from jellyfish
Implantation of the human blastocyst in the uterine wall.
Mouse implantation is also invasive, like human
Syncytiotrophoblast
Maternal
tissue
Uterine
fluid
Role of the AVE (anterior visceral endoderm) in
establishing the anterior-posterior axis of the
mouse embryo
Day 5.25
Day 5.5
Day 6.25
Cylindrical Symmetry
Otx2
Anterior
neural ectoderm
Nodal, Vg1,
Cripto (co-receptor
For Nodal and Vg1)
Endo-mesoderm
induction
Cerberus (anti-Nodal)
Dkk (anti-Wnt)
Lefty (anti-Nodal)
Bilateral Symmetry
A
P
or
hypoblast
Epiblast
ectoderm
Endo-mesoderm induction,
Primitive streak
Nodal, wnt, brachyury,
fgf expressed