Grades of actin cytoskeleton observed under a confocal laser scanning microscope using 40x objective. Grade I ¼ best (A,D; sharply stained actin filaments with continuous
cell border) and fair (B,E; slightly non-continuous actin filaments stained in cell border) quality zygotes; Grade II ¼ poor (C,F; large areas lacking actin staining in cell border or
visible actin largely aggregated into intracytoplasmic clumps) quality zygotes, 3D reconstruction (upper panel) and 2D optical section (lower panel) of the zygotes stained with
phallodine-TRITC for actin (red), and with DAPI for pronuclei (blue). Scale bar represents 30 mm. (For interpretation of the references to colour in this figure legend, the reader is
referred to the web version of this article).