Stage 15 (17 hrs 30 min)
Mid gastrula stage
Drown by T. Iwamatsu
(Abbr. )
Stage 15 (17 hrs 30 min) Mid gastrula stage: A streak is visible in the midline of theembryonic shield projecting into the germ ring area. The blastoderm covers about 1/2 of the yolk sphere. The nuclei of the marginal periblast are barely visible on the yolk sphere.