ALT Figure 8 - Working model for regeneration in H. diminuta. Overlapping regions at the head (blue bars) play two contrasting roles: proliferation and proglottidization rate are negatively regulated whereas GR maintenance is positively regulated. βcat1 expression is posteriorly biased and βcat1 is necessary to maintain stem cells in the GR, which are required for proglottid regeneration. Expression of sfrp is anteriorly biased and sfrp is necessary to maintain GR length. Signals that may link the head/brain/anterior GR to βcat1 and sfrp expression or activity remain to be identified. Serial amputation within the GR revealed increased failure to regenerate the GR and proglottids (yellow cross) at intermediate distances forming a tipping point zone that is refractory to regeneration (black shading). Both smaller and larger fragments amputated outside of the black region regenerated equivalently (green ticks).