From Neurone to Brain 4

Adult brains have 6 cortical layers and each of the neurons in the different layers have characteristic appearances and connections distinguishing the layer.

There are three stages in the development of neuronal structure-cell proliferation, cell migration and cell differentiation.

In early development the vesicle walls have two layers-the ventricular zone and the marginal zone (this faces the overlying pia).

There are 5 positions to cell proliferation:

1. Cells in the ventricular zone extend process opward toward the pia.

2. Cell nucleus migrates upwards from the ventricular to pial surface and the DNA is copied.

3. The nucleus with 2 sets of data settles back to the ventricular surface.

4. Cell retract its arm from the pial surface.

5. The cell divides in two.

Ventricular zone precursor cells are cleaved vertically and behave differently to those cleaved…