Schematic section of a chick embryo neural tube, showing the position of the nucleus in a neuroepithelial cell as a function of the cell cycle. Mitotic cells are found near the center of the neural tube, adjacent to the lumen (after Sauer 1935.)Sauer 1935 G1MG2SG1 Lumen of neural tube Gilbert S.F. Developmental Biology, 6th Edition, Figure

Scanning electron micrograph of a newly formed chick neural tube, showing cells at different stages of their cell cycles. Gilbert S.F. Developmental Biology, 6th Edition, Figure

T1 and T2 represent the time points corresponding to the moment in G1 at which the cells lose their neurogenic capacity and the beginning of G2, respectively (see mathematical model under Experimental Methods). Ventricular surface down. Interkinetic Nuclear Movement May Provide Spatial Clues to the Regulation of Neurogenesis. Murciano A, Zamora J, Lo´pez-Sa´nchez J, Frade JM Molecular and Cellular Neuroscience 21, 285–300 (2002)

A, Time-lapse videomicroscopy of radial glial cell division. Single radial glial cell at 24 h after infection (t = 0). All radial glial cells imaged had an end-foot at the ventricular surface and a radial process extending to the pia. The radial glial cell descends to the ventricular surface, divides and translocates to the top of the VZ, while its daughter cell begins radial migration. Times are indicated (min). B, After division, radial glia’s daughter migrated along the radial fibre into the intermediate zone and was confirmed to be TUJ1 positive. Neuronsderived fromradial glial cells establish radial units in neocortex. Noctor SC, Flint AC, Weissman TA, Dammerman RS, Kriegstein AR Nature 2001, 409: A B Lényeg: A radiális gliasejtek a ventrikuláris zónában jojóznak. A ventrikuláris felszínhez érve osztódnak, majd az egyik utódsejt tovább folytatja a jojózást, míg a másik utódsejt idegsejtté alakul. A Tuj1 idegsejt-specifikus marker. A radiális gliát sokáig kizárólag az asztrogliasejtek előalakjának tartották - most viszont “előléptek” idegsejt-képzésre is képes, minimum bipotenciális őssejtté (stem cell).

Schematic view of a migrating neuron. Leading edge extension occurs by polymerization of the actin meshwork, while nucleokinesis is dependent on microtubules organized with their minus end radiating from the microtubule organizing center (yellow dot). The retraction of the trailing process is generally not considered important. Neuronal migration. Lambert de Rouvroit C, Goffinet AM Mechanisms of Development 105 (2001)

Ket csikon levo C6 sejt, tubulin festes Parhuzamos lefutasu mikrotubulusok az elnyujtott sejtben

C6 tubulin, lapos sejtek

C6 tubulin, lapos sejt, 100 X nagyitas

C6, tubulin, elnyujtott sejtben a mag folott is parhuzamos lefutasu MT-ok latszanak; ugyanaz a sejt Kozel parhuzamos lefutasu mikrotubulusok az elnyújtott sejtek magja fölött,

C6 tubulin, 20X nagyitas, csikon ill. nem csikon