Lecture 10 Flashcards
What are the three zones of the mesoderm?
paraxial mesoderm
intermediate mesoderm
lateral plate mesoderm
Describe the paraxial mesoderm
thick column of mesoderm closest to and parallel with the notochord
What zone of the mesoderm becomes segmented into somites?
paraxial
What zone of the mesoderm becomes the urogenital system?
intermediate
What zone of the mesoderm splits to form lining of body cavities and mesoderm of most internal organs as well as limbs?
lateral plate
Describe the intermediate mesoderm
narrow column of mesoderm
Describe the lateral plate mesoderm
thin plate of mesoderm lateral to intermediate mesoderm
________ are initial pairs of segments of mesenchyme that begin to develop along and on either side of the neural plate in the paraxial mesoderm
somitomeres
New somitomeres are added ______ as the primitive streak regresses
caudally
_______ are more dense, bocks of mesoderm that form along the notochord
somites
In a ______ direction, a pair of somitomeresis are transformed into a pari of somites every few hours
caudal
What is the wavefront mechanism in somite differentiation?
increase in FGF-8–mitosis in mesenchymal cells in posterior primitive streak
increase in retinoic acid more anteriorly opposes action of FGF-8
What is the segmentation clock in somite differentiation?
oscillating expression of molecules in notch pathway that is expressed along a time line (90 min/ somite in chick embryo)
In the segmentation clock, ______ will become concentrated at the future anterior border of a somite and _____ will become concentrated at the future posterior border of a somite
lunatic fringe, c-hairy
In the segmentation clock, cells at the anterior border of the somite express _____ and cells of the posterior border of the anterior somite will express ____ resulting in a tissue between the two adjacent somites
Eph A (receptor) Eph B (ligand)
What is the dermomyotome?
dorsal lateral part of a somite
_____ signaling from the notochord and ____ signaling from the dorsal neural tube create a balance that causes the myotome portion to commit to the myogenic lineage
Shh, Wnt
______ inhibits _____, which would normally inhibit myogenesis
Noggin; BMP-4
What does BMP-4 produced by the lateral plate do?
suppresses myogensis in the ventrolateral dermomyotome and stimulates cells from this area to migrate from the somite into the limb bud
_____ from the myotome signals the sclerotome to produce _____, which causes the anterior and posterior borders of the each somite to form the syndetome which is the precursors of tendons
FGF, scleraxis
What does the sclerotomal portion fo each somite do?
breaks up into an anterior and posterior portion to create gaps that allow nerves to grow out form the neural tube into the epaxial segmental musculature derives from the myotomes
The future intermediate mesoderm responds to ___ and ___ and becomes intermediate mesoderm that expresses ____
BMP, activin, Pax-2
What is the intermediate mesoderm associated with forming?
pronephros, and later the mesonephros
Cranial and caudal extent of the intermediate mesoderm is dependent on expression of ____ and ____
Hox-4 and Hox-11
