Formation of Notochord Flashcards
While the primitive streak is regressing, a hollow tube forms in the middle of the mesoderm. What is this called?
Notochordal process
What forms this hollow tube?
Primitive node
What does the notochord process fuse with?
Transiently fuses with the endoderm to form the flattened notochord plate
The notochord plate then separates from the endoderm and fuses to form what?
Solid notochord
What is the function of the notochord?
Initiates neurulation
- 1st event in development of CNS
How does notochord initiate neurulation? What is this called?
Signals from notochord cause overlying ectoderm to thicken and form neural plate
Induction
What is 2nd function of notochord?
Initiates and organsises formation of the vertebrae from somites
Somites differentiate into what 3 parts?
- Sclerotome
- Myotome
- Dermatome
What does sclerotome form?
Bone and cartilage
- Sclerotome cells surround notochord to form vertebral body and surround neural tube to form vertebral arch
What does myotome form?
Skeletal muscle
What does dermatome form?
Dermis of skin
What is spina bifida?
Failure of induction of vertebral arch i.e. incomplete formation
What is feature of spina bifida?
Tuft of hair grows on back where spine hasn’t formed
What is meningocele?
Failure of correct formation of vertebral arch (spina bifida) with meninges protruding through gap
What are meninges?
Coverings of nervous system (cerebral spinal fluid bathes CNS)
