Video 2. Tribolium extraembryonic tissue rupture and withdrawal shown with amnion-specific EGFP (enhancer trap line HC079).
The embryo is shown in lateral aspect with anterior left and dorsal up, with amnion-specific EGFP expression, as well as restricted late embryonic expression domains in the legs and body segments (see also Figure 1—figure supplement 1). The movie spans late amnion morphogenesis, from 3.3 hr before rupture through late dorsal closure. Of particular note are the brighter, rounder amniotic cells in an anterior-ventral cap, in which rupture occurs. During withdrawal, the amnion everts (turns inside out), such that the surface that had faced inward toward the embryo is flipped outward to face the vitelline membrane: this is particularly apparent from 35 to 49 min after rupture as the ruptured tissue edge folds over. Time is shown relative to tissue rupture at 0 min. Images are maximum intensity projections with a gamma correction of 0.7 from a z-stack (7 µm step size for a 77 µm stack) recorded every seven minutes over a 9.9-hr time-lapse at 24°C, acquired with an Axio Imager.Z2 with ApoTome.2 structured illumination (Zeiss). Scale bar is 100 µm. Figure 4C shows a still at 21 min after rupture.