Fig. 5.
Confocal laser-scanning microscope images where microtubules are visualized by antibody (Green) and DNA by DAPI staining (Blue). (A - I) Merged view of the bright field and fluorescence images, (a - i) fluorescence images. (A, a) Just after oviposition, the sperm (sp) is visible as a faint dot at the future anterior pole of the embryo and the meiotic spindle segregates bivalent chromosomes. (B, b) Two pronuclei are reconstructed, and the male pronucleus moves toward the female pronucleus while the duplicated centrosomes around it are nucleating microtubules. (C, c) Two pronuclei meet and rotate 90° at the center of the embryo and two nucleating centrosomes are symmetrically located anterior-posteriorly. (D, d) Metaphase stage embryo. (E, e) Anaphase stage embryo, posterior centrosome moved posteriorly. (F, f) 2-cell stage embryo. (G, g) First the smaller P1 cell divides anterior-posteriorly (H, h), then the larger AB cell divides anterior-posteriorly. (I, i) Linearly-arranged 4-cell stage embryo. mp, male pronucleus; fp, female pronucleus; pb, polar body. Anterior is left. Scale bar, 20 μm.