Figure 2.

Induction of neurogenesis in postnatal mouse astrocyte cultures shows a rapid phenotypic change in a primitive astrocytic stem/progenitor cell such that it can give rise to large numbers of neuroblasts in 27 h. A mitotically active, multipotent cell emerges transiently during early stages of in vitro neuropoiesis. A. Time‐lapse microscopy of growth factor‐withdrawn subventricular zone (SVZ) cultures reveals a transient period, characterized by rapid cell divisions, leading to the initial appearance of neuroblasts within 27 h. B. BrdUrd applied at 48–72 h after the initiation of differentiation labels 95% of all generated neuroblasts. C. Clonal neurospheres were derived from cultured P8 and adult SVZ cells (left for morphological comparison). Total numbers and relative frequencies (right) of neurospheres (NS) generated from 100 000 cells per condition increase significantly but transiently at 24 h after growth factor withdrawal (WD) (*P < 0.01 for adult and P8 compared with non‐WD and 4‐d WD). D and E. Primary and secondary P8 and adult (shown here) neurospheres yield neurons (D) and glia (E). Scale bars (in µm): A, 15; B, 60; C, 200; D and E, 20. [From 58; copyright PNAS 2005, with permission.]