9.1

• Other than cell division, there must be more to neurodevelopment. If there were not, we would be nothing but an amorphous mass of homogeneous cells. To prevent this three things must occur:

  1. Cells must differentiate.
  2. Cells must make their way to appropriate sites and align themselves with the cells around them to form particular structures.
  3. Cells must establish appropriate functional relations with other cells.
• chronological list of stages of neurodevelopment:

  1. Induction of the Neural Plate
  2. Formation of the Neural Tube
  3. Neural Proliferation
  4. Neural Migration
  5. Neural Aggregation
  6. Growth of Neural Processes (Axons and Dendrites)
  7. Formation of Synapsis
  8. Neuron Death and Synapse Rearrangement
• These are developing cells that has the ability to develop into many, but not all, classes of body cells.

  Pluripotent
• These cells can develop into different cells of only one class.

  Multipotent
• Cells that can develop into only one type of cell.

  Unipotent
• True or False: The totipotent, pluripotent, and multipotent cells created during early development are all embryonic stem cells.

  True
• two important properties of stem cells:

  1. unlimited capacity for self-renewal
  2. ability of each stem cell to develop into many different kinds of cells
• Cell division that produces two daughter cells with different characteristics.

  Asymmetric Cell Division
• When a stem cell divides into two daughter cells, one of the daughter cells is a stem cell, while the other daughter cell develops into a more specific cell type.
• What makes one cell develop into a skin cell and another into a neuron?

  The ability of cells to transcribe different sections of DNA depending on their experience.
• True or False: A culture of stem cells can be induced to develop into one of many different brain cell types.

  True
• Three weeks after conception, the tissue that is destined to develop into the human nervous system becomes recognizable as the neural plate.
• A small patch of ectodermal tissue on the dorsal surface of the developing embryo.

  Neural Plate
• The ectoderm is the outermost of the three layers of embryonic cells.
• Layers of the Embryonic Cells:

  Ectoderm, Mesoderm, Endoderm
• The development of the neural plate is the first major stage of neurodevelopment in all vertebrates.
• The development of the neural plate is induced by chemical signals from an area of the underlying mesoderm layer.
• An area consequently referred to as an organizer.

  Mesoderm Layer
• The growing neural plate folds to form the neural groove, and then the lips of the neural groove fuse to form the neural tube.
• Neural tube defects can develop into severe birth defects of the CNS which are the results of errors in the folding process of the neural tube.