Fig. 2

Fig. 2 Gastrulation movements in janus-mutant embryos. (A –D) Wild-type embryo. (E–H) janus-mutant embryo. (A, E) Late blastula-stage embryos prior to gastrulation. (B, F) Dome-stage embryos; blastoderm thinning. (C, D, G, H) Shield-stage embryos; involution/ ingression movements result in the formation of the germ ring within the marginal zone. Convergence movements toward the dorsal side create the shield region (black arrow). (A, B, C, E, F, G) Lateral view with animal pole to the top. (D) Animal view, dorsal toward the right. (H) Lateral–animal view onto one blastoderm, dorsal toward the left. Asterisk indicates the animal pole of the yolk cell, close to the position of the shield. mz, marginal zone; sh, shield. Scale bar is 100 μm.