Neurulation Flashcards
When does neural plate development occur?
Late on in week 3
What does neural plate development begin with?
Ingression of cells through the primitive streak forming the notochordal process
What do ectodermal cells differentiate into?
Neuroectoderm
What happens on day 19 in reference to Neurulation?
Regression through the primitive streak and growth of the caudal end disc as well as the beginnings of neural plate segmentation
When does the neural groove begin to form?
Day 20
When does neural tube formation occur?
Day 19
What has occurred on day 19?
Expanded cranial portion
Neural plate formed
Streak extended down
Ectoderm formed ridges
Deepening of the neural groove by the ectoderm
Development of the mesoderm and coelomic cavities
What happens on day 20?
Neural groove further deepens
Cranial end thins
Somitic development beginning from the paraxial mesoderm
Lateral edges of the neural plate getting closer through folding
What happens on day 22?
Somites are visible on both sides
Neural tube closed in middle - where the cervical region will develop
Neural tube formed
Further developed intraembryonic mesoderm
What happens on day 23?
Closure of the neural tube but with anterior and posterior neuropores open
Where does secondary Neurulation occur?
In sacral and coccygeal regions
What occurs in secondary Neurulation?
Medullary cord forms the lumen that joins the neural canal
What is spina bifida occulta?
No posterior neural arch develops but the skin forms over it. Function can remain intact.
What is meningcele?
Coverings of CNS protrude posteriorly and create a bulge. The CNS stays in place but the bulge fills with CSF.
What does meningomyelocele?
The CNS protrudes with the covering so the spinal cord develops away from the vertebrae.
