Fig. 1. twin egg chambers are defective in germ cell number and oocyte specification. Anterior is leftwards in all panels. (A-G) Anti-ORB antibody. (A'-G') DAPI. Arrowheads in A',C',E',F' indicate the karyosomes in the oocytes. (G'') Phalloidin. A twin mutant ovariole typically contains egg chambers exhibiting many of these phenotypes. (A,A') Wild-type chambers have 15 polyploid nurse cells and a posterior oocyte containing Orb and a condensed karyosome. (B,B') twin^ry5/Df. Many twin egg chambers die. These chambers do not stain with Orb antiserum and they have bright, punctate DAPI staining. Egg chamber death occurs in the germarium as well (not shown). (C,C') twin^S3/Df egg chamber with five nurse cells and a normal oocyte. (D,D') twin^S3/twin^ry5 egg chamber with two nurse cells and no oocyte. (E,E') A twin^S3/twin^ry5 egg chamber with an otherwise normal oocyte in the center. (F,F') twin^S3/Df egg chamber containing 14 nurse cells and two normal oocytes. (G,G',G'') twin^ry3/twin^ry5 egg chamber with 17 nurse cells and an oocyte in the center that has undergone five divisions. Five ring canals are present but one is not easily seen in this focal plane.