Drosophila embryo stage embryonic stage 4 Temporal ordering number - 170. FBdv:00005306 Catherine Leroy Nuclear division 10-13. Polar buds divide twice and become tightly grouped at the posterior pole by the end of this stage. Nuclei visible at the rim of the embryo. Stage 4 ends with the beginning of cellularization. Duration at 25 degrees C: approx. 50 minutes (80-130 minutes after egg laying).