Figure 6

Series of longitudinal sections of an embryo with large exocoelomic cavity (ec). Artificial colors as in Figure 2. (A) Midline section characterized by the presence of the allantoic bud (Al-bud), and endodermal furrow (En-frw) close to the prospective anterior separation point. (B) Section adjacent to the midline section A. (C-D) Neighboring sections cut twice through the amniochorionic fold (ACF), which result seemingly in an anterior fold and posterior fold with their respective cavities. (E) A more lateral section reveals that the exocoelomic cavity extends around the egg cylinder. (F) Most lateral section of the series. Scale bar: 100 μm (G) Position of the longitudinal sections (A to F) on a schematic transverse section of the embryo at the level of the dashed line in A. Grey reflects the EC; no fill represents the proamniotic canal (PAC). (C'-D') Magnifications of the boxed areas shown in figure panel C and D, respectively. Scale bar: 50 μm.