Morphological and histological characteristics of the ovary and liver in the fertile, infertile, and negative control Japanese flounder groups. (A) Morphological characteristics of the normal ovary of fertile group. (B) Morphological characteristics of the ovary of infertile group. (C) Morphological characteristics of the ovary of negative control group. (D) Histological characteristics of the ovary of the fertile group. (E) Histological characteristics of the ovary of the infertile group. (F) Histological characteristics of the ovary of the negative control group. (G) Histological characteristics of the liver in the fertile group. (H) Histological characteristics of the liver in the infertile group. (I) Histological characteristics of the liver in the negative control group. pv represents oocytes at Stage III, lv represents late vitellogenic oocytes, vs. represents vacuole structure of liver. Scale bars = 2 cm in (A–C), 200 µm in (D–F), and 50 µm in (G–I).