Fig. 5

Averaged volume measurements in M. crozieri blastomeres of the first and second cleavages. a A 3D model of a 32-cell stage embryo is shown with descendants derived from the same four-cell blastomere indicated by the same colour. b A 3D model of a four-cell stage embryo is depicted showing both vegetal cross-furrow cells that meet at the vegetal pole indicated in orange. Whether the D quadrant is already specified in M. crozieri at the four-cell stage remains unclear, which is indicated here by a question mark. c–f Volumes are given as a percentage of the volume of the total embryo, which is 100% (A). d At the two-cell stage the larger cell is assumed to represent blastomere CD and the smaller cell blastomere AB. e At the three-cell stage division of blastomere CD most likely precedes the division of blastomere AB. f At the four-cell stage the largest blastomere is always one of the vegetal cross-furrow cells and is interpreted as the D blastomere. c′–f′ All volume measurements come from five-angle 3D multiview reconstructions and have been orientated with a view from their vegetal side. Only a single plane of the 3D reconstructed stack is shown. Scale bar = 100 µm