Fig. 6. Larval eye primordia arise from an initial state comprising a group of cells that require L/Ser function for growth and maintenance. Removal of L/Ser function in these initial cells can completely eliminate eye. During late first instar of development, the pnr⁺ cells emerge and initiate the expression of downstream Iro-C genes, which results in DV specification of eye. Establishment of DV lineage in eye restricts the L/Ser requirement to the ventral cells only. pnr⁺ and Iro-C⁺ cells become independent of L/Ser requirement. Therefore, the initial state prior to DV specification is probably equivalent to ventral eye in nature.