Term
| Marginal, Mantle and Ependymal Zone |
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Definition
| Zones in descending order of the neural tube. |
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Term
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Definition
| Composed of the Mantle and ependymal zone. They are the layers closest to the ventricle, the center of the neural tube that is to become the ventricals of the CNS |
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Term
| Interkinetic Nuclear Migration |
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Definition
| Observed "up-and-dow" movement of the nuclei of progenitor cells in the neural tube. Processes extend from the ependymal to the pial surface. The nucleus of the cells move up and down between the mantle and ependymal zone depending on the stage of cell cycle it is in. |
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Term
| Symmetric/Asymetric Cell Division |
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Definition
| Cells in the VZ unergo 1-2 cell cycles per day. The division can be symetric in which case both cell keep on dividing. However if the division is assymetric, then the larger one of them will become post-mitotic and migrate into the marginal zone while the other will continue dividing. |
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Term
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Definition
Cells undergo a series of stages through which they produce other cells. G1->S->G2->M->G1...etc.
During S phase, the genetic material is replicated and during M, actual mitosis occurs. |
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Term
| Cell cycle in the developing CNS |
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Definition
| The cell cycle duration lengthens as they mature and become older. Cells cycles in developing organisms are much shorter and thus these cells produce more daugter cells. This lengthening is mostly due to increases in G1 phase. |
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Term
| Thymidine birthdating method |
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Definition
Cells are treated with Thymidine that has incorporated tritium (H3). The tritium-thymidine is incorporated in the cells DNA only during S-phase. Hence if your culture has high levels, then they underwent mitosis already.
If medium levels are detected, then mitosis occured several times after exposure
If none is detected, then cells never underwent S-phase after exposure |
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Term
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Definition
Cells that haven't differentiated fully yet. Their methylation is presumybly low and hence they can still become or give rise to cells of many tissue types. Not commited yet.
? |
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Term
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Definition
| Same concept as tritium-thymidine birthdating.Except with Uracil that has a bromide group attached. antibodies with a flourescent dye can be then attached to the incorporated Uracil and thus these cells can be detected. |
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Term
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Definition
The generation of new neurons:
Birthdating techniques tell us that large neurons become postmitotic earlier than smaller neurons (I guess presumably also in deeper layers)
and that phylogenetically older part sof the brain develop before more recently evovled structures
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Term
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Definition
| Cell cycles are controlled by a group of proteins called cyclins. These interact with cyclin dependent kinases (Cdk) |
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Term
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Definition
| Cdk's are kinases with which cyclins interact. These are used to activate (phosphorylate) necessary proteins for the cell cycle to appropriately continue |
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Term
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Definition
Processes that determine wither a neuroblast become neurons or glial cells are likely to invovle extracellular signalling. Some of the signals that promote gliagenesis are PDGF, NT-3, IGF1
These factors are produced by astrocytes
Production of oligodendrocytes may be due to activity of adjacent neurons
And activation of the notch pathway leads to the generation of astrocytes... the activation of notch in these cells leads to the hes pathway whcih inhibits expression of proneural genes |
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Term
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Definition
| Postmitotic cells migrate away from the VZ towards the pial surface (marginal zone) using radial glia (progenitor cells) |
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Term
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Definition
In the developing cortex, 2 layers of cells form in the marginal cells... these form the pre-late
Postmitotic cells will then migrate in between the two layers of the pre-plate. |
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Term
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Definition
| Neural progenitor cells of the early cortex that extend from the VZ to the pial surface. They help postmitotic cells they generate to "climb" up through the layers into their appropriate location. |
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Term
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Definition
| Alternative form of migration in which the cell itself stretches processes to the pial surface and "pulls" itself to the correct layer |
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Term
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Definition
| Alternative form of migration in which a cell moves laterally along the layers |
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Term
| Three secondary zones of neurogenesis |
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Definition
Three zones within which neurogenesis occurs (even as adults).
The external granule layer
The subventricular zone
Hippocampal granule cell precursers |
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Term
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Definition
| Migrating cells from the SVZ will form chains and "climb" over each other as a migrating mechanism |
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Term
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Definition
| Cell adhesion molecules, cell surface proteins that allow granule cells to climb along glia. |
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Term
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Definition
| Cell surface protein similar to CAMs that is produced by granule cells in culture. It is necesary for neurons to climb over glial cells |
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Term
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Definition
| Another protein that is critical for migration of neurons in general. KO or mutation of reelin genes in mice shows that the layers don't form appropriately and is used as a model for schizophrenia |
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