Cytoskeletal organization and cell polarity are altered in <i>Ofd1^Δ</i>

<p>^{<b>4–5/+</b>}<b> embryos.</b> Staining for F-actin with fluorescent phalloidin reveals a reduced signal and actin disorganization at the cell apex in severely affected <i>Ofd1^Δ</i>^4–5/+ mutants (B) with respect to wild-type <i>Ofd1⁺</i>^/+ embryos (A). Scale bars: 200 µm. A higher magnification of the actin boundary indicates a reduced thickness in mutant embryos (inset B) compared to wild-type <i>Ofd1⁺</i>^/+ embryos (inset A). Immunofluorescence with β-catenin reveals a continuous band in wild-type embryos (C) but a punctuate and discontinuous band in <i>Ofd1^Δ</i>^4–5/+ severe mutants (D). Scale bars: 100 µm. Immunofluorescence analysis of ZO1, a marker of tight junctions, shows a discontinuous pattern along the margin of the ventricular surface (F) compared to wild-type embryos (E). Scale bars: 50 µm. Immunostaining of Par3 with a discontinuous pattern along the cells lining the ventricular zone in <i>Ofd1^Δ</i>^4–5/+ severe mutant embryos (H) compared to wild-type embryos (G). Scale bars: 50 µm. White arrows in panels D, F, H indicate expression discontinuity along the apical membrane. Immunostaining of Ki67 (in red) and Par3 (in green) indicate reduced Ki67 expression and presence of abnormally located cortical progenitors, which tend to protrude outside the ventricular zone in <i>Ofd1^Δ</i>^4–5/+ severe mutant embryos (J) compared to wild-type embryos (I). Scale bars: 200 µm. vz: ventricular zone. Immunofluorescence analysis of Caspase 3 revealed no difference in the number of apoptotic cells in wild-type embryos (K) and in <i>Ofd1^Δ</i>^4–5/+ severe mutant embryos (L). Dashed rectangles designate enlarged areas indicated in panels K′ and L′ showing apoptotic cells in the ganglionic eminence (GE) region. Scale bars: 500 µm.