Fig. 8. Models for furrow birth and reincarnation. Green arrows show inductive interactions, red symbols show inhibitory influences. Purple arrows and Hh in birth model indicates first ommatidial induction and purple ommatidia are the first ones produced. Blue furrows and arrows indicate Hh progression signal from the newly established ommatidia, and blue ommatidia are those produced by this mode of Hh induction. Orange arrows show progressive furrow re-initiation along the lateral margins and orange ommatidia are those induced by Dpp.