Figure 7. Cellularisation and time classification scheme for M. abdita during cleavage cycle 14A.

Images captured from time-lapse movies showing the membrane morphology at mid-dorsal positions are shown on the left-hand side for time classes T1–T8 and for gastrulation. Starting times after egg laying for each time class are shown in the bottom left of each image in hrs:min(:sec). Schematic overlays show vitelline membrane (thick black line), nuclei (red circle, oval or rectangle), and invaginating membrane front (thin black line). Grey nuclei indicate the size of the nuclei at T3 for reference. Descriptions of features used to distinguish each stage are provided on the right (see text for details).