Fig. 2. An oocyte is specified in osk^A87/Df(3R)p^XT103. (A,B) Whole mount antibody staining of osk^A87/Df(3R)p^XT103 ovaries (B) shows that Staufen is not enriched in the osk^A87mRNA null oocytes compared with wild type (A). (C-J) In contrast, the oocyte markers BicD (Suter and Steward, 1991), Orb (Lantz et al., 1994), Bruno (Webster et al., 1997), and Par-1 (Shulman et al., 2000; Tomancak et al., 2000) accumulate in a single, posterior cell in both wild-type (C,E,G,I) and osk^A87/Df(3R)p^XT103 (D,F,H,J) egg chambers, indicating that early steps in oocyte specification occur normally in the mutant. (K,L) DAPI staining of chromatin in stage 4 wild-type (K) and osk^A87/Df(3R)p^XT103 (L) egg chambers. The compact structure of the karyosome (arrow) is detected within the wild-type oocyte nucleus. osk^A87/Df(3R)p^XT103 mutant oocytes show a fragmented karyosome structure (arrow).