Neurulation and Somitogenesis Flashcards
What is neurulation?
The formation of the vertebrate nervous system in embryos
How does the notochord develop?
Some mesodermal cells migrate cranially in the midline of the mesodermal layer forming the rod-like notochordal process
What is the neuroectoderm?
Cells derived from the ectoderm within the nervous system
What does the notochord arise from?
Mesoderm
What does the neural tube arise from?
Ectoderm
How does the neural tube form?
The neural plate folds in on itself to form the neural tube which later differentiates into the spinal cord and brain.
Describe the first step in the process of neurulation
- Neuroectodermal tissues differentiate from the ectoderm and thicken into the neural plate, The neural plate border separate the ectoderm from the neural plate
Describe the second step in the process of neurulation?
The neural plate bends dorsally, with the two ends eventually joining at the neural plate borders, which are now referred to as the neural crest.
Describe the third step of neurulation?
The closure of the neural tube disconnects the neural crest from the epidermis. Neural crest cells differentiate to form most of the peripheral nervous system
Describe the fourth step of neurulation?
The notochord degenerates and only persists as the nucleus pulpous of the intervertebral discs. Other mesoderm cells differentiate into the somites, the precursors of the axial skeleton and skeletal muscle
What are somites?
Paired cubodial bodies divide from the differentiation of the paraxial mesoderm
What do somites differentiate to form?
Cartilage of the axial skeleton
Muscles of the rib cage, limbs and back
Cells that contribute to the connective tissue of the dermis
What are the specific regions of the somite?
Sclerotome (bone)
Myotome (muscle)
Dermatome (connective tissue)
What are neural crest cells?
Multipotent neural crest cells migrate widely in embryo and give rise to many nervous structures
What happens to the nueral tube?
Neural tube becomes narrower and longer
Accompanied by lateral folding of the neural plate
Fusion of the neural folds
Separation of the nueral tube from the overlying ectodermal sheet
What is the adult derivative of the notochord?
Notochord persists in adulthood as the nucleus pulpous of intervertebral discs
