During the induction of Japanese eel maturation, administering maturation-inducing steroids (MIS) or their precursors at an inappropriate maturational status is a major cause of poor egg quality. In this study, we investigated the feasibility of controlling oocyte maturation progress by rearing in cold and warm water to manipulate the timing of MIS administration. Mature females with oocytes at the migratory nucleus stage were reared for two terms (3 days to 1 day and 1 day to 0 days before MIS administration) at 20/20 °C, 20/15 °C, 15/20 °C, or 15/15 °C, and the maturational status was monitored based on their lipid droplet morphology and oocyte diameter. Oocytes matured faster at 20 °C than at 15 °C in either term. Next, the mature females were reared at 15 or 20 °C depending on the maturational status of each female 3 days and 1 day before MIS administration; the immature females were reared at 20 °C to accelerate their maturation. Consequently, the maturational status of most females was similar at MIS administration. After improvement, this method would lead most females to the optimum maturational status at MIS administration by properly rearing in cold and warm water.

在日本鳗鱼成熟的诱导过程中，在不适当的成熟状态下使用成熟诱导类固醇 (MIS) 或其前体是导致卵子质量差的主要原因。在这项研究中，我们研究了通过在冷水和温水中饲养来控制 MIS 给药时间来控制卵母细胞成熟进程的可行性。在迁移核阶段具有卵母细胞的成熟雌性在 20/20 °C、20/15 °C、15/20 °C 或15/15 °C，并根据其脂滴形态和卵母细胞直径监测成熟状态。卵母细胞在 20 °C 下成熟得比在 15 °C 下更快。下一个，根据每只雌性在 MIS 给药前 3 天和 1 天的成熟状态，将成熟雌性在 15 或 20°C 下饲养；未成熟的雌性在 20°C 下饲养以加速其成熟。因此，大多数女性的成熟状态在 MIS 管理中是相似的。改进后，这种方法可以通过在冷水和温水中适当饲养，使大多数雌性在 MIS 给药时达到最佳成熟状态。