Fig. 4

Morphological characterization of ovarian oocytes in the chg.l+/+ and chg.l−/− females. A-C Schematic illustrations of the structure of the ovarian chg.l+/+ medaka egg under different magnifications. B Enlarged illustration at the position of the rectangle in A. C Enlarged illustration at the position of the rectangle in B, showing microvilli (v) from the follicle cell layer (FCL), ooplasm, and pore canal (PC). D-F Light micrograph (D) and Transmission Electron micrographs (E-F) of the chorion in the chg.l+/+ female. G-I Light micrograph of the ovarian oocyte (G) and Transmission Electron micrographs (H-I) of the chorion in the chg.l−/− female. F and I Magnified images of the chorion marked by white squares in E and H, respectively. Symbols – Panels E-F and H-I OL and dark blue arrowheads with a black outline mark the position of the chorion externa. IL and brackets mark the position of the chorion interna. Panel F White arrows mark the position of the pore canal. Panel I Red arrows mark large pore canal-like structures. Scale bars in D and G = 100 μm; in E and H = 5 μm; and in F and I = 0.5 μm