True b. Is inactivated by the degradation of cyclin. True c. Is activated by the action of cdc25 phosphatase. Phosphorylates histone H1 to induce chromosome supercoiling prior to cell division. Describe how 6 layers of the cerebral cortex are formed from cells in the neural tube. Cells at the lumen are mitotic.
Cells move away from the lumen after completing mitosis.
Postmitotic cells move through previously-formed other layers to the outside surface of the neural tube. Each successive wave of cells moves to the outside. Radial glial cells aid in this migration. The diagram at the right is of a human embryo and placenta after 40 days of gestation. Identify each of the structures indicated by a line.