Inhibition of cortical astrogliogenesis by <i>hGFAP-cre</i> mediated <i>orc3</i> gene deletion in class II mutants.

<p>(<b>A–F”</b>) Young astrocytes were stained using anti-BLBP antibodies (red in <b>A–F</b> and <b>A”–F”</b>), and nuclei were labeled by DAPI staining (blue in <b>A'–F'</b> and <b>A”–F”</b>) in control and <i>orc3</i> mutant cortices at P3 (<b>A–B”</b>), P5 (<b>C–D”</b>) and P7 (<b>E–F”</b>). No obvious differences were observed in the density of BLBP positive astrocytes between control (<b>A–A”</b>) and mutant (<b>B–B”</b>) cortices at P3. However, obvious reductions were observed in mutants (<b>D–D”</b>) as compared to controls (<b>C–C”</b>) at P5. Young astrocytes also appeared more elongated in the mutant cortex at P5. By P7, BLBP positive astrocytes were almost completely eliminated from mutants (<b>D–D”</b>) as compared to controls (<b>C–C”</b>). (<b>G–I</b>) Quantification of BLBP positive cell density in P3 (<b>G</b>), P5 (<b>H</b>), and P7 (<b>I</b>) control and mutant cortices. Statistical analysis by Student's <i>t</i> test showed no significant changes in mutants at P3 (control, 685.6±19.1/mm²; mutant, 716.0±18.8/mm²; <i>P</i> = 0.27, n = 9), but significant decreases in BLBP positive cell density at both P5 (control, 974.8±38.6/mm²; mutant, 447.7±117.4/mm²; <i>P</i> = 0.001, n = 11) and P7 (control, 1033±47/mm²; mutant, 701±14/mm²; <i>P</i> = 0.0001, n = 4). Scale bar in (<b>F”</b>), 200 μm for (<b>A–F</b>).