Photographs of zebrafish and mouse ovaries and testis. a A zebrafish ovary after being dissected into several pieces, followed by fixing with 4% PFA/PBS and washing with PBS. b A mouse ovary after being fixed with 4% PFA/PBS and washed with PBS. c-f A mouse testis after being fixed with 4% PFA/PBS and washed with PBS (c) that was held with forceps (d) and cut into two pieces with a razor blade according to the median plane (e and f). Bars: 2 mm

Double fluorescence in situ hybridization of mos (red) and cyclin B1 (green) mRNAs in zebrafish ovaries. DNA is shown in blue. a-c A zebrafish ovary section showing localization of mos (a) and cyclin B1 (b) mRNAs in a fully grown oocyte. A merged image is shown in (c). The mos and cyclin B1 mRNAs were localized at the animal polar cytoplasm beneath the micropyle (m). fc, follicle cells; c, chorion. d-f High resolution imaging of the oocyte shown in a-c. The insets are enlarged views of the boxed regions. The mos and cyclin B1 mRNAs were distributed in the animal polar cytoplasm of oocyte as different granules. Bars: 50 μm in a-c, 10 μm in d-f

Double fluorescence in situ hybridization of cyclin B1 (red) and dazl (green) mRNAs in zebrafish ovaries. DNA is shown in blue. a A follicle consisting of stage Ia oocyte. Insets are enlarged views of the boxed region showing cyclin B1 mRNA (upper), dazl mRNA (middle) and a merged image (lower). b A follicle consisting of stage Ib oocyte. Insets are enlarged views of the boxed region showing cyclin B1 mRNA (upper), dazl mRNA (middle) and a merged image (lower). c A follicle consisting of stage II oocyte. The inset is an enlarged view of the boxed region. d A follicle consisting of stage III oocyte. The inset is an enlarged view of the boxed region. Arrowheads indicate cyclin B1 RNA granules localized at the animal polar cytoplasm of oocytes. Arrows indicate dazl RNA granules distributed in the vegetal polar cytoplasm of oocytes. GV, germinal vesicle; Bb, Balbiani body; fc, follicle cells. Bars: 20 μm in a and b, 50 μm in c and d