Fig. 1. Localization of eomes in the early zebrafish. (A) Northern blot comparing eomes transcript levels at one-cell (0.3 hpf), eight-cell (1.25 hpf), 128-cell (2.25 hpf), 512-cell (2.75 hpf), 1000-cell (3 hpf), sphere (4 hpf) and dome (4.3 hpf) stages. Actin was used as a loading control. Exposure time, 7.5 hours. (B-D) Sections of adult ovaries: GV, germinal vesicle. (B) Stage I oocyte (20-140 µm), staining is uniform throughout cytoplasm (arrowhead). (C) Stage II oocyte (0.14-0.34 mm), eomes hybridization can be seen along the cortex of the oocyte (arrowhead). (D) Stage III oocyte (0.34-0.69 mm). eomes mRNA is detected cortically (arrowhead) and throughout the cytoplasm. (E,F,H,K) Whole-mount embryos, animal pole is toward the top. (G,J) Sections with the animal pole toward the top. (E) Activated egg, eomes is detected in the cytoplasmic streams in the yolk and in a gradient along the V/A axis. The arrow marks the region of most intense hybridization at the yolk/blastodisc junction. (F) The expression pattern in a four-cell-stage embryo is similar to that in E. (G) Section of a four-cell stage embryo showing the distribution of eomes mRNA. The arrowhead marks the most intense region of eomes expression at the yolk-blastomere junction. (H) Expression of eomes is maintained in vegetal to animal gradient in a 32-cell-stage embryo. (I) Nearly ubiquitous zygotic eomes expression at the 1000-cell stage. (J) Section of an oblong/sphere-stage embryo. eomes mRNA is detected in vegetally located cells and is absent from the YSL (arrow). (K) Sphere-stage embryo, eomes hybridization is reduced in the animal pole and is most intense in cells closest to the yolk.