Notch and Delta RNAi affects multiple steps in oogenesis. Wildtype (A-D), Notch (E-H), and Delta RNAi two (I-L) and four days after dsRNA injection, respectively (M-P) (dpi). Roman numerals refer to egg-chambers in corresponding stages of oogenesis. Ovarioles were stained for f-actin with Phalloidin (red) andfor DNA with Hoechst. (blue). In panels C,G,H,K,L,O,P only the Hoechst staining is shown. Panels (B-D), (F-H), J-L), and (N-P) are close ups of the ovarioles shown in A,E,I, and M, respectively. (A-D) In wildtype, pro-oocytes (A, asterisks) enter the vitellarium and eventually become encapsulated by somatic follicle cells (B, dotted line). Individual follicles become subsequently separated by interfollicular stalk cells (A, arrowhead; B, arrow). As judged by morphology (i.e. size of the nuclei) (C, top view of the follicle cell epithelium of the ovariole in A), follicle cell nuclei are still in mitotic cycle. During late stages of oogenesis, yolk is taken up by the oocyte from the hemolymph (vitellogenesis). The vitellogenic oocyte considerably increases in size, while follicle cell nuclei switched from mitotic (D, arrow) to endocycle (D, arrowhead). (E-H) Two days after injection of Notch dsRNA, the follicle cell epithelium appears disorganized (E, arrows). Interfollicular stalks are absent (E, arrowhead) and compound follicles (i.e. egg-chambers that comprise of more than two oocytes) are observed (F, arrow). Already at pre-vitellogenic stages, follicle cell nuclei are increased in size (E, arrows; G,H, top views of the follicle cell epithelium of the ovariole in E), indicating that the nuclei have become polyploid (compare C to G). (I-L) Also upon Delta RNAi, follicle cell nuclei seem to become polyploid prematurely (I, arrows; K,L top view of the follicle cell epithelium of the ovariole in I). The follicle cell epithelium appears rather patchy (I, arrows), stalk cell were missing (I, arrowhead), and compound follicles are observed (J, arrows). (M-P) Four days after injection, Delta RNAi phenotypes are increased in strength. Oocytes accumulate in large compound follicle (I,N) and also the size of follicle cell nuclei further increases (M, arrows; O,P, top views of the follicle cell epithelium of the ovariole in M). Egg-chambers seem to maximize their area of contact (M, arrowhead). All panels: anterior to the left. Asterisks label pro-oocytes that enter the vitellarium.