Lecture 15 Flashcards
all skeletal muscle originates in either ______ or ____
somites or somitomeres
What are the stages of differentiation of skeletal muscle tissue myogenic cells
- originate in somites
- resemble mesenchymal cells
- restricted to muscle forming line
- mitotic cells
Mitotic cells are kept in labile state by what?
FGF and TGf-B
What are the stages of differentiation for myoblasts?
- derived from myogenic cells
- postmitotic
What are the stages in differentiation for myotubes?
- formed when myoblasts line up and adhere to one another
- requires CAMs
- involved in mRNA and protein synthesis
- characterized by appearance of actin, myosin, troponin and tropomyosin
- formation of myofibrils with sarcomeric arrangement
- nuclei move to periphery
When do satellite cells become mitotic and what happens?
in times of stress
and C Met receptor is binding site for HGF (hepatic growth factor)
describe primary myotubes
- formed by fusion of earliest (embryonic) myoblasts
- may already be distinguished as fast or slow in some species
- differentiation occurs before innervation
Describe secondary myotubes
- smaller than primary
- formed alongside primary from late (fetal) myoblasts
- presence of motor axons may be necessary to form secondary myotubes
- contained within same basal lamina and are electrically coupled
FGF and ____ maintain myogenic cells in labile state
TGF-B
Loss of mitotic capability is due to what?
due to p21 due
what is the MyoD family capable of?
able to convert non muscle cells to cells capable of expressing muscle proteins
epaxial muscles arise from _______ of myotome
dorsal lip
Epaxial tendons arise from _____ within somites
sydetome layer
Hypaxial muscles arise from ______ of myotome
ventral buds
Tendons of hypaxial muscles arise from ______ of mesoderm
lateral plate
limb muscles arise from ________
ventrolateral demomyotome
tendons of limb muscles arise from _______
lateral plate mesoderm
Where are the muscles of the head and neck mostly derived from?
paraxial somitomeres
extra ocular muscles arise from _____
prechordal plate
cranial musculature derived from the ________ mesoderm
unsegmented paraxial
Some cranial musculature is derived from ____
splanchnic mesoderm
Where is cardiac muscle derived from?
splanchnic mesoderm
Early cardiac muscle does not express _____
MyoD
