St13-5.9hpf

late gastrula (5.9 hours), the blastopore is in the posterior position and is nearly closed. The embryo elongates anteriorly. The neural plate has more than 6 rows and the A-line neural rows (I and II) begin to curve (the start of neurulation). The large b6.5 progeny arrive together at the midline.

Dorsal view of three-dimensional image (upper), 50% section image (middle), and longitudinal section image (lower). Dashed lines in middle indicate the position of the section. Scale bar = 50 micro m. b.p., blastopore; n.p., neural plate.