1. Chapter 15- Lateral mesoderm and endoderm
Fig mesoderm lineages
Recall lineages
Fig. 12.4
Paraxial
Head
Somite
Cartilage,
skeletal,
dermis
Intermediate
Kidney, gonads
Notochord
Lateral
Circulatory,
Body cavity,
extraembryonic
3 regions:
Fig mesoderm lineages
a. _________________
-becomes body cavity wall
b. _______
-becomes the body cavity
c. ___________________
-becomes body cavity wall and the the heart

2. How does the heart develop??
c. Splanchnic mesoderm
Lateral 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)
72hr
28hr
27hr
Myocardium
3. Endocardium tubes _______
4. Mycocardium ________
5. Heart begins beating even while ________ is occurring

3. Fig. 15.13- “extra” archs in mammal development
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
____________ an organism must:
Obtain ___________before the intestine develops
Use __________ before there are lungs
Excrete _________ before there are kidneys
Fig “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

4. Blood vessels and blood cells are intimately connected
Blood vessel formation
Lateral mesoderm
1. Vasculogenesis
Fig
Blood vessels and blood cells are intimately connected
BMP
Endothelial cells line __________
Angiogenic cell cluster
(_________________)
Fig
Primitive blood cells
__________
__________cells

5. Transcription factors in vasculogenesis
Lateral mesoderm
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 _____________)

6. ________ stabilizes capillary network
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 _______!
________ stabilizes capillary network
VEGF plays key role
______ recruits pericyte cells to ensure __________ of capillaries

7. Arterial (__________) Venous (______)
Lateral mesoderm
2. Angiogenesis
Arteries vs. veins??
Arteries have _____________in cell membranes
Veins have _________________ (called EphB4) in cell membranes
Arterial
(__________)
Venous
(______)
Fig
Functions of the EphrinB2/EphB4 system
Ensure that arteries only link up with _____, not other arteries
Ensure capillary fusion only occurs with like cells (e.g. only arteries with arteries)

8. Many organs make their own angiogenesis factors
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 ___________

9. Development of Blood Cells Fig. 15.20
Lateral mesoderm
Development of Blood Cells
Fig
____________ – embryonic cells capable of producing many cell types, including other ______________
Largest population of stem cells is in the _______________
“Committed”
“Differentiating”
“Differentiated”
Stem Cell
(CFU-M,L)
B-cell lineage
T-cell lineage

10. Myeloid precursor cell
Lateral mesoderm
Development of Blood Cells
The stem cell (CFU-M,L) also gives rise to another cell lineage:
“Committed”
“Differentiating”
“Differentiated”
Stem Cell
(CFU-M,L)
B-cell lineage
____________
Platelets
_________
T-cell lineage
Myeloid precursor cell
Eosinophils
___________
Fig
____________
___________ factors that direct blood cell formation are termed “_________”
Note that this is the point of ___ _______- cells are __________ to a becoming only one cell type

11. Angiogenic cell cluster
Lateral mesoderm
Development of Blood Cells
Blood development (hematopoiesis) occurs in two phases:
1. _____________
Angiogenic cell cluster
(blood islands)
Occurs in blood islands in mesoderm near the yolk (recall fig )
Supplies developing embryo with oxygen
___________ inhibit blood and blood vessel formation
Fig
__________- disappear later in development
Example- In mouse, stem cells originate in yolk sac, then later in AGM region
2. ___________
Formed in nodes of mesoderm surrounding aorta (in a region called the _________________________ (AGM) region)
Lasts the _______ of the individual
Fig

12. (Esophagus,stomach,small intestine,colon)
Endoderm
Recall Fig. 12.4
Embryonic endoderm gives rise two ____
Endoderm
Buds into
__________ tube
(Esophagus,stomach,small intestine,colon)
_____, _________, pancreas
Primitive gut
endoderm
__________ tube
_________
1. _______ endoderm – tissues are derived from _________________
Auditory cavities
Tonsil walls
_______(T-cell development)
______________
Pharyngeal arches
Fig. 13.1
_____(sprout form base of forth arch)

13. 2. ____________ endoderm
Liver bud
Stomach
The _________________ buds out form the foregut, then branches to form ________, _________ and ___________
Gall Bladder
Pancreas
(ventral)
Pancreas
(dorsal)
The ____________ is actually formed by the fusion of two distinct buds (one ventral and one dorsal)
Fig

14. 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. 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
Fig
Week 4 (humans)

16. Problem Solution Four problems of a land-dwelling egg
Day 2 chick embryo
Problem
Solution
1. ____________
Amnion secretes amnionic fluid into ________
2. ____________
______ exchanges gases
3. ____________
_________ supplies nutrients from blood vessels in yolk
Day 9 chick embryo
4. ____________-
________ holds waste (vestigal in humans)
Fig