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0. Basic Concepts / Orientations
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1. What are the five major regions of the mesoderm? I suggest you be able to draw a
diagram of their relative positions.
Dorsal
Mesoderm -
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2. What major tissues are formed from each mesodermal territory?
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2. What major tissues are formed from each mesodermal territory?
Splanchnic Mesoderm
Visceral mesoderminner branch of lateral mesoderm
lays alongside the endoderm (yellow)
Lateral Mesoderm
Becomes part of the musculature of
the digestive system
Becomes incorporated into the
endodermal structures (intestinal
muscles) which eventually becomes a
composition of both endodermal and
mesodermal tissue.
Somatic Mesoderm
outer branch of lateral mesodermLays alongside body wall (ectoderm)
Somatic Somitic dont confuse with somiteSoma = body
Somitic = segmented mass of mesoderm in the vertebrate animal
Coelom :
Lateral plate forms the coelom with its two branches.
Definition of coelom cavity surrounded by mesoderm.
Most of our guts or organs are hanging out in the coelom
Literally a carved out (saved) area were organ s will be
allowed, their formation to expand into.
Echo 09:26 12:30
Slides 8-9
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3. What is presomitic mesoderm?
4. What is paraxial mesoderm?
Dorsal (top) view Notochord
is beneath the neural tube
(cant see)
Anterior-Posterior view (slice)
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5. What is a somite?
A somite is a condensed pinched off bit of paraxial mesoderm.
It is the source of:Spine, Muscles, Tendons, & underlying tissues of the skin.
It contains stems cells that will differentiate into
* Cartilaginous eventually
becomes boney. Ribs andVertebrae for example
* A large portion
of skeletal muscle
*Dermis this is underlying the epidermis of our skin
(beneath the epidermis) and is derived from the
Dermatome.
* A portion of the Skeletal Muscle
Prof Thomsen didnt discuss 4&5
but he did talk about the Head
paraxial (pre-somitic) mesoderm.
Headsome of the skull
structures & vertebrae of thehead are derived from paraxial
mesoderm.
These structures are derived from
the somites way up in the front
of the body (most anterior)
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6. Describe the progression of somite formation over time along the A-P axis
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7. What is the function of FGF expression in the presomitic mesoderm?
8. What is the evidence for a somite clock?
9. What is the Hairy gene, and how does its expression change as the somite clock runs?10. What is the proposed/speculated pathway for the somite clock?
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11. What does Hairy/Hes gene expression regulate?
12. How does the Notch signal transduction pathway work? What is the ligand(s)?
Notch Regulated Genes:
Targets Include:
Hairy1/Hes
Lunatic Fringe
Delta
& others