Z5001524
Introduction
Neurulation is divided into primary neurulation and secondary neurulation. Primary neurulation begins on the mid-week 3. The neural plate will start folding along the medial axis and will eventually form the neural tube. This will then contribute to the brain and part of the spinal cord of the central nervous system [1] . This page will mainly focus on primary neurulation by looking at its establishment of the neural tube and some other components in the central nervous system in the end of week 4.
Process of primary neurulation
<html5media height="600" width="800">File:The_process_of_neurulation.mp4</html5media>
Summary of primary neurulation [2] [3]
| Process | Events |
|---|---|
| Neural plate formation | - The ectodermal cells on the medial axis will differentiate into neuroectoderm with pseudostratified columnar epithelial cells.
- The rest of the ectodermal cells will become non-neural ectoderm. - These two regions will be separated by the neural plate borders. - The notochordal process will fuse with the endoderm and form notochordal plate . |
| Shaping of the neural plate | - Narrowing of the transverse plane
-The neural plate borders will point upwards |
| Folding of the neural plate | - The neural plate will undergo bending by rotating the neural plate around the median hinge point above the notochord and give rise to the neural groove
- Neural plate borders → Neural folds - The notochordal plate will detach from the endoderm and form the notochord which aids the rotation of the neural plate |
| Closure of the neural groove | - The dorsolateral hinge points will move closer to each other continuously until the epithelial layer consist of the roof plate of the neural tube and the non-neural ectoderm.
- The neural fold will transform into the neural crest and stay in the mesoderm with the neural tube. |
Additional information
What forms the median hinge point and dorsolateral hinge points ?
The notochord will signal the cells in the dorsal midline to reduce the cell height and increase their cell diameter in order to form a wedge. These cells will then become the median hinge point cells and form a median hinge point[4]. On the other hand, the dorsolateral hinge points are done by increasing the cell height on the neuroectodermn [4].
References
- ↑ <pubmed>7747264</pubmed>
- ↑ Gilbert SF. Developmental Biology. 6th edition. Sunderland (MA): Sinauer Associates; 2000. Formation of the Neural Tube. doi:http://www.ncbi.nlm.nih.gov/books/NBK10080/
- ↑ Schoenwolf, G.C., Bleyl, S.B., Brauer, P.R. & Francis-West, P.H. (2009). Larsen's human embryology (4th ed.). New York; Edinburgh: Churchill Livingstone.
- ↑ 4.0 4.1 <pubmed>19206138</pubmed>
