substage of immediately preceded by developmental stage blastoderm stage embryonic stage 5 gastrula stage embryonic stage 6 FlyBase_development_CV FBdv:00005318 Stage 6 begins when the ventral furrow becomes apparent, an event which is followed rapidly by the formation of the cephalic furrow. Stage 6 ends when the pole cells have adopted a dorsal (horizontal) position at the posterior. Duration at 25 degrees C: approximately 10 minutes (170-180 minutes after egg laying). Temporal ordering number - 230.