Myogenesis Flashcards
What are the 3 signals that specify muscle development from the somites? Where are they coming from?
Wnt from the dorsal neural tube
Shh from the notochord
BMP from the epidermis
What does Shh signalling from the notochord do to the sclerotome cells?
Causes to express Pax1 and lose N-cadherins and undergo an EMT
What happens to the dermamyotome when the sclerotome cells undergo an EMT?
The dermamyotome splits into the dermatome and the myotome, which is in the centre
What does the myotome give rise to?
Abaxial and primatial muscles
What two transcription factors specify the myotome to become muscle?
Myogenic regulatory factors: Myf5 and MyoD. They activate muscle specific genes
Are myotome cells specified before or after they undergo the EMT?
Before
What signal induces the migration of myotome cells?
FGF
What do myotome cells do once they reach the area they’re supposed to go to?
Start multiplying
What are embryonic muscle cells called?
Myoblasts
What do myoblasts do when they stop dividing?
Align themselves in a really organized way and fuse into myotubes
What do myotubes become?
Muscle fibers
Why are muscle fibres able to contract so strong?
Multi-nucleate
Why are myoblasts an example of morphogenesis?
They respond to signals and specifications and change their cell adhesion and organization
Do vertebrates keep producing more muscle fibres?
No, we have a set number of muscle fibres and just expand the ones we already have
What determines the amount of muscle fibres an organism develops?
Myostatin - a hormone
What happens if there is a mutation in myostatin that knocks out its function?
Excessive muscle growth, because it limits the growth of muscles to a normal amount
Is every muscle cell specified during development?
No, muscle stem cells stay unspecified
Where in the dermamyotome do muscle stem cells originate from?
Central part
Why aren’t muscle stem cells specified?
They don’t express myogenic regulatory factors, which keeps them unspecified
When do muscle stem cells become specified?
In event of injury. They become specified and the cell cycle gets reactivated to fix the injury
