Fig. 2. Cell shape changes in the PE of different imaginal discs. Temporal sequence of epithelial morphogenesis in wing (A-E), leg T2 (F-H) and eye (I-M) discs at different larval stages. -Spectrin outlines cell morphology (A-M). Each panel displays an image of the PE (left) and longitudinal section (right) taken through the center of the disc (indicated by arrows only in A,F,I). In longitudinal sections, the PE is oriented left of the disc lumen. White arrowheads indicate squamous PE cells, grey arrowheads mark margin cells. Bolwig's nerve is indicated by red asterisks. Broken yellow lines mark the AP boundary, anterior is towards the left. MF, morphogenetic furrow.