Fig. 4

H-wounds inflicted on planarians with altered levels of Wnt signaling induce patterned outgrowths. a, b Simple incisions applied to β-catenin-1 RNAi planarians induced accessory heads, which were not observed when ERK activation was inhibited by PD, or in control RNAi animals. Sample numbers indicated in each image. In contrast, ectopic heads formed in existing posterior tissues were unaffected by PD treatment. Arrow, ectopic eyes; sFRP-1, anterior marker; ndk, marker for the brain region. c Similarly, ectopic lateral outgrowths but not posterior heads in homeostatic β-catenin-1 RNAi animals were inhibited by treatment with PD. d–e Outgrowths were also induced by lateral incisions inflicted on APC (d) or patched (e) RNAi planarians, which undergo direct^28,29,30 or indirect³¹ ectopic activation of Wnt signaling. To increase the penetrance of outgrowth formation in (a), (d), and (e), two incisions were made instead of one. Numbers refer to injured areas (two per animal); scale bars: 100 μm