Fig. 3. polyhomeotic is required specifically within somatic cells to control somatic cell differentiation. (A-F) ph⁰ mosaic follicles stained with DAPI (A,C,E, gray; D, blue), Propidium Iodide (B,F, red), anti-ß-Gal (A',C', green), anti-Orb (A'', red), anti-Hts (B', white; C'', red), anti-Eya (D,D',E'', red), or anti-Fas III (F', insert and F'', white) antibodies. Mutant clones for ph⁰ are detected by the absence of anti-ß-Gal antibody staining (A',C', white tracing) or by the absence of GFP fluorescence (B,D',E',F', green). (A-A'') Mosaic compound follicle (A), bearing a small ph⁰ mutant somatic cell clone (A') and exhibiting three oocytes (A''). (B,B') ph⁰ prefollicular cells (asterisks in insets), in contrast to wild-type cells (B', arrow), are found at the periphery and do not extend thin processes over germline cysts. (C-C'') Abnormal mosaic ph⁰ and ph⁺ interfollicular stalk. Hts accumulates at the membrane of interfollicular stalk cells (C''). (D-D') In a late stage follicle, a clone of ph⁰ cells exhibiting five polar cells (D,D', marked by the absence of anti-Eya staining). (E-E'') ph⁰ cells (E') expulsed from the follicular epithelium (E, bracket) express the Eya protein (E''). Arrowheads in E'' point to pairs of polar cells at each follicle extremity that do not express Eya. (F-F'') ph⁰ follicular clones (F', insert) upregulate Fas III compared with adjacent ph⁺ follicular cells (F''), but nonetheless express lower levels of Fas III compared with polar cells (F'', arrowhead). ph⁰ clones are delimited by a dotted line in A' and C'.