Notes

How do you get from a fertilized egg and pluripotent cells to the highly specialized neural structures?

Principles of Mammalian Neural Development

• Tissue Polarity: The tissue is polarizing.
• Cellular Polarity: also cells have to be polarized.

Neurulation It is the start of the formation of the CNS. It is the formation of the vertebrate nervous system in embryos. The notochord induces the formation of the CNS by signaling the ectoderm above it to form the thick and flat neural plate. The neural plate then folds in on itself to form the neural tube, which will then later differentiate into the spinal cord and brain. In the figure: (top) Neuro-epithelial layer already showing signs of elongation of cells (notochord not present). (middle) Neural groove forming. (bottom) Neural tube formed with overlying ectoderm and underlying notochord.

How to visualize dividing cells (and their progeny)? Dividing cells like stem cells are those that give rise to neurons. To visualize them we can use:

• Endogenous marker (pH3. Ki67, mitotic figures): are proteins that selectively express when the cell is dividing.
• Thymidine analogues (BrdU): these analogues are integrated into the DNA when it is doubling and they can be detected through antibodies.
• Retroviruses: they cannot cross nuclear membrane, so they can only enter the cell when it is dividing and can be later identified.
• Transgenic Lineage Tracers
• Fusion Plasmids (tubulin, histones).