Fig. 2. Early gastrulation stages of the rabbit embryo. (A) Whole blastocyst at a pre-primitive streak stage (6.0 d.p.c.); the plane of focus is on the blastocyst wall containing the embryonic disc. (B) Stage 1 with smooth anterior contour (epiblast-trophoblast junction) of the disc indicating the position of the AMC. The posterior contour (arrows) is more ragged. (C) Stage 2 with the ‘posterior gastrula extension’ (PGE), a sickle-shaped area of reduced density that lies posteriorly to the ragged posterior contour (arrows) seen at stage 1. (D) Stage 3 with primitive streak (s) in the midline of the PGE. The former posterior margin is still visible (arrows). Scale bars: 1.3 mm in A; 250 µm in B,C; 270 µm in D.
