Fig. 2

Limb patterning program expressed in the developing anterior segment. For each gene: left to right, anterior whole-mount view, lateral whole-mount view (anterior left), cross-section (anterior is down), cartoon summary is specific to only the anterior segment expression, excluding brain and retina expression for clarity. Dotted white outline in lateral view outlines the perimeter of the eye. A–C Defining cell populations in the developing anterior segment at stage 23. A, A’, A” DpS-Crystallin expression in the anterior segment at stage 23, expressed in the proximal, central cells corresponding with the LC2 cells (lc2). Expression is also apparent in the lens. B, B’, B” Expression of DpSix3/6. B” Expression is apparent in the distal, central cup cells (cc) and the proximal-marginal (pm) anterior segment cells. The proximal-central cells (lc2) lack expression of DpSix3/6. C, C’, C” DpLhx1/5 expression. C” Expression of DpLhx1/5 is found in the distal-marginal cell (dm) population. Expression is excluded from the central cup (cc). D–G Expression of the limb patterning program genes. Summary of the proximodistal expression of each Drosophila homolog during proximodistal patterning of the limb is shown on the right. H Prd-like homolog Homeobrain (Hbn) expression in the distal, central cup cells. a, arms; aco, anterior chamber organ; cc, cup cells; dm, distal-marginal cells; e, eye; l, lens; lc2, LC2 cells; m, mantle; mo, mouth; pm, proximal-marginal cells; r, retina; y, yolk. Anterior segment highlighted in grey in the cartoon. Orientation abbreviations: M, marginal; C, central; Pr, proximal; D, Distal; A, anterior; P, posterior. Scale for whole-mount anterior view is 500 μm. Scale for lateral whole-mount view 200 μm. Scale for sectioned images 50 μm