library_construction_protocol: Midguts were dissociated with elastase on a rotator with periodic pipetting for 1 hour at 27°C. The cell suspension was filtered through a 100 μm cell strainer, and pelleted at 200g for 5 min at 4°C. Cells were pooled together, resuspended in 1× PBS with 0.1% ultra-pure BSA, and filtered through a 70 μm cell strainer. For collecting EE lineages, GFP-positive cells were sorted out by FACS. scRNA-seq libraries were prepared using Chromium Next GEM Single Cell 3ʹ Reagent Kits v3.1, following the manufacter's instructions.