Fig. 3. Increased cell cycle exit in the Atrx-null cortex during early neurogenesis results in increased generation of TBR1⁺ and SATB2⁺ early-born neurons.

(A) Pregnant female mice were subjected to a 24-hour BrdU pulse prior to sacrifice. Ki67 and BrdU immunostaining in E12.5 (pictured) and E14.5 control and Atrx-null cortex. Scale bar: 50 µm. Arrowheads indicate BrdU⁺Ki67⁻ cells that have exited the cell cycle. Cell cycle exit indices were calculated by measuring the ratio of BrdU⁺Ki67⁻ cells to total BrdU⁺ cells in E12.5 (B) and E14.5 (C) control and Atrx-null cortex (n = 3). (D) TBR1 and SATB2 immunostaining in E14.5 control and Atrx-null cortex. Scale bar: 50 µm. (E) Quantification of the proportion of TBR1⁺ and SATB2⁺ cells as a percentage of total DAPI⁺ cells (n = 3). Data expressed as mean ± S.E.M. *P<0.05.