Development of Somites and the Nervous System Flashcards
Somites differentiate segmentally into what three parts?
Sclerotomes
Dermatomes
Myotomes
What part of the somite do the vertebral bodies form from?
Sclerotome
Sclerotomes will develop into vertebrae in the vicinity of what?
notochord
Why embroynically do spinal nerves exit between the vertebrae?
Sclerotomes split and recombine to produce intersegmental vertebrae
In the IV discs, what does the nucleus pulposus form from?
nucleus pulposus
In the IV discs, what does the anulus fibrosis form from?
Sclerotome cells
Where do ribs develop from?
Mesenchymal condensations called costal processes that are associated with vertebral arches
How does the sternum develop?
Fusion of 2 longitudinal bars of mesenchymal tissue, called sternal bars
The dermomyotome differentiates into the dermatome and myotome. What does the dermatome contribute to the development of?
Dermis of the neck, back, and trunk
remember that most other dermis is derived from somatopleure
_________ invade limb buds and form limb musculature
somitic myoblasts
Myotomes differentiate into _______ and ________ muscle
epimeric (dorsal) and hypomeric (ventral)
What gives rise to deep back muscles?
epimeres
What gives rise to muscles of lateral and ventral body wall, including intercostals, abdominal girdling muscles and rectus abdominus?
Hypomeres
What is piebaldism and what causes it?
Absence of melanocytes in the skin and hair, therfore unable to make melanin pigment.
A lack of migration of the neural crest prevents melanocyte formation
All ganglion in the body are derived from what?
neural crest
