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Fig. 1. Expression of the odd-genes is associated to the margin-peripodial cells
of the eye disc during development. (A,B) Schemes of late
L2/early L3 (A) and late L3 (B) eye discs. (A) Posterior margin cells trigger
retinogenesis in the adjacent eye primordium (ep) by producing Hh. (B) Once
triggered, retinal differentiation progresses anteriorly (eye). (C)
Cross-section through the line in B shows the peripodial and margin cells
(green) overlaying the differentiating eye primordium. (D,E)
Confocal images of the posterior region of a third larval stage (L3) disc
through the peripodial (Pe, D) and disc proper (Dp, E) layers, stained with
phalloidin-FITC and Elav (a photoreceptor marker used in this and following
figures). The margin (ma) is a thin strip of cells adjacent to the
posterior-most row of photoreceptors. (F) Confocal z-section
through the same disc showing the three cell types (schematized below).
(G) Confocal z-section through the posterior region of a L3
odd-GAL4>GFP disc, co-stained with Eya. odd is restricted
to the Pe and margin. (H-O) Patterns of expression of the four odd
genes in L2 (H-K) and L3 (L-O). Expression of odd is monitored by the
odd-GAL4 reporter (H, left; L) or with an anti-Odd antibody (H,
right), and that of drm (I,M), bowl (J,N) and sob
(K,O) by RNA in situ hybridization. The patterns of drm and
odd seem identical. (H, left) Propidium iodide marks nuclei. (H,
right) Rhodamine-phalloidin stains actin. (L) Arm expression marks cell
membranes. Arrowheads indicate the margins. Discs are oriented with posterior
towards the right and dorsal upwards.
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