Fig. 3

Cleavage, gastrulation, epiboly and reversion in O. vulgaris. Bright-field images of embryos in cleavage (a-d), at Stage I (e), Stage II (f), Stage III (g), Stage IV (h), Stage V (i), Stage VI (j), Stage VII.1 (k) and Stage VII.2 (l). Nuclear staining of Stage V (i′), Stage VI (j’), Stage VII.1 (k′) and Stage VII.2 (l’) embryos imaged with light sheet fluorescence microscopy (LSFM). Black arrowheads indicate the progression of epiboly, red arrowheads the borders of the embryo proper. At Stage VII, O. vulgaris embryos undergo the first reversion (m) and can be observed in distinct phases/ topologies during reversion (n-o) with LSFM. Scale bars represent 200 μm. Abbreviations: a, arm; ey, eye; ma, mantle; mo, mouth; st, statocyst; yc, yolk cells