(A-H) Infection of POE::Glucre animals using lentiviruses producing either an shRNA targeting Ngn3 transcripts (E-H - Xu et al., 2008) or producing a scrambled shRNA (based on the former; A-D). Two weeks post-infection, Ngn3 knockdown pancreata (at the indicated magnifications) display an efficient 61% diminution in Ngn3 production (Xu et al., 2008, A, E and Table S6), but also a 69% decrease in insulin- (B, F, D, H) or glucagon- (C, G) expressing cell numbers (Table S6) compared to scramble-infected counterparts.