Fig. 2. Dpp is required for the anterior-most part of the operculum in the absence of Grk signaling. Anterior is to the left. (A,D,G) DIC micrographs of anterior eggshell regions. (B,E,H) SEM micrographs of anterior eggshell regions. (C,F,I,K) Stage 14 egg chambers stained for DAPI (blue) and Fas3 (operculum cells, red). (A-C) Wild-type. The operculum can be subdivided into three different regions (I, II, III). The white arrow marks the collar. (D-F) grk^HF/grk^2B6 eggs have region I operculum cells surrounding the micropyle (yellow arrow) and stage 14 chambers show corresponding Fas3 expression. (G-I) In eggs from females carrying large Med mutant follicle cell clones the region surrounding the micropyle (yellow arrow) is reduced in size and lacks follicle cell imprints. (I) Med¹³ mutant follicle cell clones in a stage 14 egg chamber lack Fas3 expression. White lines mark the clone boundaries. The inset shows a DIC micrograph of the same egg demonstrating the integrity of the follicular epithelium at the anterior pole. Med¹³ mutant cell clones showed reduced levels of DAPI staining in later egg chambers. However, the integrity of the follicular epithelium was not affected. (J,K) Eggs and egg chamber from females misexpressing dpp in a grk^HF/grk^2B6 background. (J) Darkfield micrograph of non-deposited egg (stage 15). Inset shows a DIC image of the abnormally thickened micropyle. (K) Stage 14 egg chamber. Fas3 expression is also found in random patches in more central positions of the main body follicle cells (marked by yellow arrow).