Exam 3: Limb Development 2 Flashcards
What cells are the limb bud mesenchyme derived from?
Lateral plate mesoderm
What are limb muscles derived from?
Somitic ventral dermomyotomes
What causes cartilage formation to be constricted to the central core of the limb bud?
Wnt-7a from overlying ectoderm
What is expressed to induce pre-cartilage formation in the limb bud central core?
BMP’s
In what direction does differentiation of cartilaginous skeleton occur?
Proximodistal
In what direction does digit formation occur?
5 –> 1
What marks the point of joint formation?
Condensed zone of cells
What inhibits BMP in the region where the joint will form?
Noggin
T/F: All components of the joint are formed by skeletal elements.
False, Articular cartilages by skeletal elements & other components by additional mesenchymal cell condensations
Which part of the cartilage/bone forming in the limb bud remains intact where the joint forms & forms the joint capsule?
Perichondrium
Proximal cells of limb bud produce _____, while pre-muscle cells in the somite express _____.
Scatter factor.
c-met, receptor for scatter factor
What do migrating pre-muscle cells express?
Pax-3 & N-cadherin
What is pre-muscle cell differentiation in the limb bud dependent on?
Wnt-6 expressed by the ectoderm
What is expressed by the connective tissue associated with the muscle masses?
Tcf-4
T/F: Individual muscle morphology is determined by connective tissue.
True
At what week do motor axons originate from the spinal cord?
5th
If the forelimb rudiment is removed, nerves of the brachial plexus are _____ and cells in ganglion may be _____ by up to 50%.
Smaller.
Reduced
If an additional limb rudiment is transplanted, what happens to the spinal nerves?
Local spinal nerves supply transplanted limb & increase in thickness.
Ganglia increase as much as 40%
If the forelimb rudiment is cut out and transplanted near the original one, _____ nerves are deflected in the direction of the transplanted limb.
Brachial
If an additional limb is transplanted next to host limb, _____ nerves develop _____ & they are usually not functional.
Brachial.
Branches
Earlly vasculature arises from endothelial cells from _____, _____, & _____.
Aorta, cardinal veins, & angioblasts
What inhibits formation of blood vessels?
Overlying ectoderm
