Figure 3.

Confocal sections through living embryos at 25°C after injection with WGA–Alexa488. (A) Injection during phase 2 and observation during phase 3 at time 0 (purple, middle) and 18 min later (blue, bottom). Double arrow marks the growing lateral labeled membrane region. (B and B′) As in A at time 0. The basal extent of the label (B, arrow) is adjacent to, but excluded from the FC (B′, arrowhead). A nucleus (N) is outlined. (C) Injection during late phase 3 and observation during phase 4 at time 0 (red, middle) and 12 min later. The arrowhead points to a gap of unlabeled membrane appearing apical–laterally while the basal–lateral labeled membrane (double arrow) translocates basally. (D) WGA–Alexa488 (green, 1st label) was injected in phase 2, transferred laterally during phase 3 similarly to A. At the onset of phase 4, WGA–rhodamine (red) was injected. The embryo is shown shortly after. (E) Diagram summarizing the data. The apical and lateral membrane in early phase 3 (green) is transferred laterally as new membrane is inserted apically (red, middle). New insertion apical–laterally (yellow) follows in phase 4 (bottom) as the green region moves basally in register with the FC (black).