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. 2000 Jan 1;20(1):283–293. doi: 10.1523/JNEUROSCI.20-01-00283.2000

Fig. 3.

Fig. 3.

The developmental profiles of neuronal progenitor cells was followed in low-density culture. A, B, The dissociated cells derived from E13.5 telencephalons of wild-type (A) and Hes1−/− mice (Hes1−/−, B), were clonally cultured, and phase-contrast photos of identical fields were obtained at 1, 2, 3, and 4 DIV. The letters a–f in each panel are placed beside the colony derived from the same single progenitor cell. For instance, in colony b in the wild-type culture (A), the single progenitor cell at 1 DIV underwent several cell divisions, and four cells were observed at 2 DIV. They extended their processes toward the neighboring colony a and appeared to form network-like connections by 3 DIV. This network of cells became better established, and cells showed a more differentiated neuronal morphology with long and branched processes by 4 DIV. These cells also appeared to keep dividing until 4 DIV. In contrast, in coloniesd and f in theHes1−/− culture (B), single progenitor cells divided once by 2 DIV, but the resulting cells soon fell into apoptosis (d at 4 DIV; f at 3 DIV). The Hes1−/− neuron ein (B) extended thick processes rapidly by 2 DIV, but network-like connections were not formed as in the case of the wild-type culture at 4 DIV. C, Proliferating profiles of neuronal progenitor cells. The number of cells that originated from 100 neuronal progenitor cells in the low-density culture are summarized at the indicated day below the line graph. In the wild-type culture, progenitor cells kept increasing in number during the observation period. In contrast, the initial proliferation of progenitor cells was not disturbed by the Hes1mutation, but the cells stopped proliferating after 2 DIV and decreased in number (by apoptosis) in the Hes1−/−culture. D, The average number of neurons derived from a single neuronal progenitor cell. Numbers of neurons are represented in each bar as the means ± SEM of ∼100 NPs of three independent experiments. *p < 0.05 in comparison with the wild-type control of the same stage. The embryonic stages of the mice are indicated below each bar. The mean N/NP was reduced inHes1−/− mice, irrespective of the developmental stage.