Fig. 7. Aberrant formation of cytoskeletal structures in Pax6 mutant (rSey²/rSey²) EGL cells. (A,B) PKH26-labeled cells emigrating from a microexplant of E21 EGL observed at 1 DIV. Wild-type cells (A) have long straight neurites, while mutant cells (B) protrude short neurites, occasionally bifurcated and/or extruding lamellipodia in the midst of the shafts (arrow). (C,D) Scanning electron micrographs of microexplant cultures (3 DIV). Wild-type cells (C) possess thin growth cones at the tip, most of which simply taper off. Pax6 mutant cells (D) expand large growth cones with massive lamellipodia. (E,F) Distribution of F-actin (green) and microtubules (red) in growth cones. In comparison with wild type (E), an excess amount of F-actin accumulates in the large growth cones of Pax6 mutant EGL cells, accompanied by invasion of microtubules (F).

(G) Quantification of growth cone size. Live cells labeled with PKH26 were observed at 1 DIV. The growth cone area was measured as the number of pixels in the graphic image. Data are indicated as mean±s.e.m. (P<0.005). Scale bars: 10 µm.