Download Chapter 15- Lateral mesoderm and endoderm

Chapter 15- Lateral mesoderm
and endoderm
Recall lineages
Fig. 14.1- mesoderm lineages
Notochord
Intermediate
Kidney,
gonads
Fig. 12.4
3 regions:
Fig. 14.1- mesoderm lineages
Paraxial
Lateral
Circulatory,
Head Somite
Body cavity,
extraembryonic
Cartilage,
skeletal,
dermis
a. _________________-becomes body cavity wall
b. _______ -becomes the body cavity
c. ___________________ -becomes body cavity
wall and the the heart
Lateral mesoderm
c. Splanchnic mesoderm
How does the heart develop??
25hr
26hr
Fig. 15.3
___________
1. Splanchnic mesoderm
halves begin to ______
2. These cells differentiate into ___________
(heart lining and valve precursors
and ______________ (heart muscles)
28hr
27hr
Myocardium
3. Endocardium tubes _______
4. Mycocardium ________
5. Heart begins beating even
while ________ is occurring
72hr
Blood vessel formation
Lateral mesoderm
2 steps- 1._____________ and 2. ____________
Note: Blood vessels form independently of the heart, then link up
Some background Info
Constraints on blood vessel construction
1. ____________ an organism must:
•
•
•
Obtain ___________before the intestine develops
Use __________ before there are lungs
Excrete _________ before there are kidneys
Fig. 15.13- “extra”
archs in mammal
development
2. ________________•
Six pairs of __________ loop
out- these enable primitive fish
gills to oxygenate blood, but
these serve no obvious purpose
in mammals and birds.
3. ____________- Blood flows easier through large vessels, yet efficient
____________requires small vessels and ________________ blood
Solution- Large vessels branch into very small ones with overall
more cumulative volume capacity
Blood vessel formation
1. Vasculogenesis
Blood vessels
and blood cells
are intimately
connected
Lateral mesoderm
Fig. 15.14
BMP
Endothelial cells line __________
Angiogenic
cell cluster
(_________
________)
__________
Fig. 15.16
Primitive
blood cells
__________cells
1. Vasculogenesis
Transcription factors in vasculogenesis
1. _______ is required for
_____________formation
2. ________ is required for
blood island and blood vessel
formation
VEGF is a target for ______________
“Tumors gotta eat”
3. ______ is required proper
blood vessel formation
(involved in communication
between endothelial cell and
_____________)
Lateral mesoderm
Lateral mesoderm
2. Angiogenesis
Definition- _________ and _______ of capillary beds, arteries and veins
Note- Capillary
networks of each
organ arise within
the organ itself,
not from larger
_______!
VEGF
plays key
role
________
stabilizes
capillary
network
______
recruits
pericyte
cells to
ensure
__________
of
capillaries
Lateral mesoderm
2. Angiogenesis
Arteries vs. veins??
•Arteries have _____________in cell membranes
•Veins have _________________ (called EphB4) in cell membranes
Arterial
Venous
(__________) (______)
Fig. 15.17
Functions of the EphrinB2/EphB4 system
1. Ensure that arteries only link up with _____, not other arteries
2. Ensure capillary fusion only occurs with like cells (e.g. only
arteries with arteries)
Lateral mesoderm
2. Angiogenesis
Many organs make their own angiogenesis factors
•Example- placenta
Developing placenta secretes ___________ to promote
angiogenesis, then later secretes ___________________ to
inhibit angiogenesis
Angiogenesis plays key role in tumor development
•A tumor must induce _________________ in order to ______
•Hence, if use a drug that inhibits this
______________, can possibly slow cure some
___________
Lateral mesoderm
Development of Blood Cells
Fig. 15.20
____________ – embryonic cells capable of producing many
cell types, including other ______________
Largest population of stem cells is in the _______________
“Committed”
Stem Cell
(CFU-M,L)
B-cell lineage
T-cell lineage
“Differentiating”
“Differentiated”
Lateral mesoderm
Development of Blood Cells
The stem cell (CFU-M,L) also gives rise to another cell lineage:
“Committed”
Stem Cell
(CFU-M,L)
B-cell lineage
“Differentiating”
“Differentiated”
____________
Platelets
_________
Myeloid T-cell lineage
precursor cell
Fig. 15.21
Eosinophils
___________
____________
___________ factors that
direct blood cell formation
are termed “_________”
Note that this is the point of ___
_______- cells are __________ to a
becoming only one cell type
Lateral mesoderm
Development of Blood Cells
Blood development (hematopoiesis) occurs in two phases:
1. _____________
Angiogenic cell
cluster
• Occurs in blood islands in mesoderm
(blood islands)
near the yolk (recall fig. 15.16)
• Supplies developing embryo with oxygen
• ___________ inhibit blood and
blood vessel formation
Fig. 15.16
• __________- disappear later in development
2. ___________
•Formed in nodes of mesoderm
surrounding aorta (in a region called
the _________________________
(AGM) region)
•Lasts the _______ of the individual
Example- In mouse, stem
cells originate in yolk sac,
then later in AGM region
Fig. 15.24
Endoderm
Recall Fig. 12.4
Embryonic endoderm gives rise two ____
Endoderm
Buds into
__________ tube
Primitive gut
endoderm
(Esophagus,stomach,small intestine,colon)
__________ tube
_____, _________,
pancreas
_________
1. _______ endoderm – tissues are derived from _________________
Auditory cavities
Tonsil walls
_______(T-cell development)
Fig. 13.1
Pharyngeal
arches
______________
_____(sprout form base of forth arch)
2. ____________ endoderm
The _________________ buds
out form the foregut, then
branches to form ________,
_________ and ___________
The ____________ is actually
formed by the fusion of two
distinct buds (one ventral and
one dorsal)
Liver bud
Stomach
Gall Bladder
Pancreas Pancreas
(ventral) (dorsal)
Fig. 15.29
What directs formation of liver from the endoderm??
The notochord (and
mesenchyme) produces
factors that ________
liver induction
The __________________
secretes ____ that
________ the factors that
inhibit
liver induction
Thus, _____signals the
__________ region of
the endoderm to
become liver
Fig. 15.30
The respiratory tube
• ______ are one of the last _________ to differentiate
• Alveolar cells of the lung produce _________ at 34 weeks gestation
• Thus, a premature infant cannot breathe properly
foregut
Pharynx
trachea
Lung buds
esophagus
Week 4 (humans) Fig. 15.31
Four problems of a land-dwelling egg
Problem
Solution
Day 2 chick
embryo
1. ____________ Amnion secretes amnionic fluid into ________
2. ____________
______ exchanges gases
3. ____________
_________
supplies nutrients
from blood vessels
in yolk
4. ____________- ________ holds
waste (vestigal in
humans)
Day 9 chick embryo
Fig. 15.33