Fig. 2. Overexpression of ph leads to defects in follicle formation. All ovarioles are oriented with the anterior towards the top left corner. (A,B,C) DAPI staining of 4061/+ (A) and 4061/+; da-Gal4/+ (B,C) ovarioles. (B) Compound follicle with a `curved' aspect to the follicular epithelium (arrow). (C) The first cysts in the germarium are contained within a single epithelium, without follicle individualization (arrowhead); arrow points to apposed follicles. (D) Representation of P{y+}UAS and PlacW insertions at the ph locus in the P[4061] and ph<sup>lac</sup> lines, respectively. The P{y+}UAS is inserted 99 pb upstream of the ATG, in the sense orientation, whereas the PlacW is inserted in the first intron. (E-H) Control (F) and mosaic ovarioles (E,G,H) in which ph overexpressing cellular clones are detected by the expression of a GFP reporter construct (E',G',H'-H'''). Ovarioles are stained with DAPI (E,F,G,H), anti-Orb antibodies (E'') and anti-Fas III antibodies (F',G'',H'-H'''). Compound follicle (E), with a `curved' epithelium, results from encapsulation of two oocytes as visualized by Orb staining (E'', arrowheads). (G-G''') Abnormal accumulation of germline cysts in an entirely clonal germarium (compare G'' and F'); prefollicular cells that overexpressed ph began to migrate over germline cysts (G'', asterisks) but failed to completely individualize them. (H) Compound follicle with two germline cysts encapsulated together; this follicle contains four groups of polar cells (arrowheads, H'-H''': three different focal planes of the same follicle).