Fig. 5. Prolonged expression of Cut maintains follicle cells at an immature stage. Cut-misexpressing cells are marked with co-expression of GFP (green in A,B,D,F) or Cut staining (green in E,G). (A,A') FasIII (red in A and white in A') continued to be expressed in follicle cells overexpressing Cut (outlined) in stage 9 egg chamber, whereas neighboring wild-type follicle cells no longer expressed FasIII, except in the polar cells (arrowhead) and the stalk cells (not shown). (B,B') Big brain (Bib, red in B and white in B'), a stalk-cell marker, was expressed in the stalk cells (arrow) but not in the main-body follicle cells even if Cut was overexpressed. (C) The Eya expression pattern during early oogenesis. Eya protein (shown in red) was expressed in the germarium and in all follicle cells except the polar cells up until stage 8, but the expression was lower after stage 6. PH3 (shown in green) was used to indicate the M phase of the mitotic cycle. (D,F) Eya (red in D,F and white in D',F') was continuously expressed in follicle cells overexpressing Cut after stage 7 and until stage 10. Eya was not expressed in stage 12 egg chambers (F,F' with increased background). (E,G) Polar-cell fate marker A101 (stained with anti-ß-gal, red in E,G and white in E',G') was only expressed in polar follicle cells (arrowhead in E and E') in the middle stage, whereas it was expressed in main-body follicle cells overexpressing Cut after stage 10.