Vegetal daughters of first quartet micromeres, 1q2, form the prototroch. (A, B, D, E, G, H, J, K) Z-stacks of merged, confocal images through late stage 6 larvae 5 days after labeling 1q2 micromeres with DiI. The channels are DiI (red), phalloidin (green) and TO-PRO-3 (blue). (C, F, I, L) Cropped, digitally magnified, z-stacks of merged, confocal images through the prototroch of late stage 6 larvae. The channels are DiI (red), phalloidin (green) and TO-PRO-3 (blue). (C', F', I', L') Single channel images of DiI shown in (C), (F), (I) and (L), respectively. The arrow in (L) points to a DiI-labeled prototroch cell that is separate from the rest of the clone. The blastomere labeled with DiI is indicated to the left of each row and the view is indicated in the lower-left corner of each panel (dors = dorsal, vent = ventral, llat = left lateral, rlat = right lateral). Anterior is to the left in all ventral, dorsal and left lateral images, and to the right in all right lateral images. The position of the mouth is indicated with an asterisk.