Fig.6.

Migration and proliferatory behavior of Drosophila intestinal stem cells during metamorphosis. A, B: Boundary region of midgut (left) and hindgut (right) of late third instar larva (L3). Adult midgut progenitors (AMPs) are labeled by Esg reporter construct (red; A); adult hindgut progenitors, labeled by Byn reporter construct (red; B) are concentrated in hindgut proliferation zone (hpz). They can be distinguished from Byn-positive differentiated larval hindgut (hg) by their small size and high packing density. C, D: Lineage tracing of adult midgut progenitors (C) and adult hindgut progenitors (D). Progenitors were labeled at early larval stage by stably expressing a lacZ reporter by Esg-Gal4 (C) or Byn-Gal4 (D), respectively. Labeled progeny of progenitors at in adult gut are depicted. Note that progeny of AMPs (C) occupy proximal portion of Malpighian tubules (ureter, ure), but not posterior segment of midgut (mgps). This part of the midgut is populated by descendants of adult hindgut progenitors (mgps in D). E, F: Lineages produced by division of presumptive intestinal stem cells during the pupal period. The lacZ tracing construct was expressed by esg-Gal4 in 24h pupa. At 48h (E), lacZ expression (blue) is confined to presumptive stem cells (pISCs; GFP-positive, green), indicating that division of these cells from 24–48h results merely in the production of additional pISCs. At 72h, lacZ-positive cells include pISCs (green), but also endocrine cells (aen; labeled by anti-Prospero; red). This result demonstrates that the Pros-positive cells are born during pISC divisions taking place between 48 and72h after onset of metamorphosis.