Fig. 1. milt mutant oocytes do not form normal Balbiani bodies. (A-D) Prefollicular cysts: (A) schematic; mitochondria (green) in wild-type cysts (broken outlines, B) and milt⁹² null mutant cysts (broken outlines, C) associate, as expected, with the fusome (magenta). By contrast, mitochondria in class II milt^EY01559 cysts (D, broken outlines) accumulate prematurely at the middle of the fusome (arrows). (E-H) Forming follicles: (E) schematic; mitochondria in milt⁹² null mutants remain at the anterior of the oocyte (G, small broken outline) and fail to form a normal Balbiani body (yellow broken outline) as in wild type (F). In milt^EY01559 mutants, excess mitochondria move into the oocyte (H) to form an abnormally large Balbiani body. (I-L) Stage 5 follicles: (I) schematic; in wild type (J), mitochondria are sparse and evenly distributed. Mitochondria remain tightly packed at the anterior of milt⁹² oocytes (K, arrow). In milt^EY01559, mitochondria fill the cytoplasm of the oocyte (L). (M-P) Stage 9 follicles: (M) schematic; the number of mitochondria in wild type (N), milt⁹² (O) and milt^EY01559 (P) is similar. However, in milt^EY01559, mitochondria cluster at the anterior of the oocyte (P, arrow), where microtubule minus-ends focus (M). (B-D,F-H,J-L,N-P) ATP synthase, green; (B-D,F,H) 1B1, magenta; (J-L,N-P) phosphotyrosine, magenta; (G) ß-galactosidase marks wild type cells (blue). Scale bars: 10 µm in A-L; 20 µm in M-P.