Effects of rearing period in seawater on induced maturation in female Japanese eel Anguilla japonica
Effects of rearing period in seawater on induced maturation in female Japanese eel Anguilla japonica
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DOI：
10.2331/fishsci.64.77
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发表时间：
1998-02-01
影响因子：
1.9
通讯作者：
Okuzawa, K
中科院分区：
文献类型：
--
作者：
Kagawa, H;Iinuma, N;Okuzawa, K
以日本鳗鲡（Anguilla japonica）为材料，研究了海水饲养时期对激素诱导成熟的影响。在海水中保存3个月的雌鳗（30月龄）卵母细胞完成卵黄发生的注射次数显著少于在海水中保存1周的雌鳗。受精率和孵化率在两个实验组的卵母细胞之间没有显著差异。在使用6个月大的雌性进行的实验中获得了类似的结果。这些结果表明，长期饲养在海水中的鲑鱼垂体提取物卵巢成熟的反应性增加。组织学观察表明，在海水中保存3个月的雌鱼卵母细胞变大，达到初级卵黄球期，而在海水中保存1周的雌鱼卵母细胞处于油滴期。电镜观察表明，海水中3个月的雌鱼脑垂体中促性腺激素细胞开始活跃。这些结果是首次发现，在人工饲养条件下，没有任何激素处理的培养幼鳗卵黄发生触发。这些形态学的结果表明，长期饲养在海水中诱导卵黄发生的女性，导致在缩短的时间内完成的注射鲑鱼脑垂体提取物的卵黄发生。
The effects of rearing period in seawater on induced maturation by hormonal treatments were examined in the cultured female Japanese eels Anguilla japonica. The oocytes of female eel (30 month old) kept in seawater for 3 months completed vitellogeneisis by significantly smaller number of injection of salmon pituitary extracts than those of female kept in seawater for one week. Fertility and hatching rates were not significantly different between the oocytes of the two experimental groups. Similar results were obtained in the experiment which was performed using 6-month older females. These results indicate that long term rearing in seawater increased responsiveness to salmon pituitary extract in ovarian maturation. Histological observation revealed that oocytes of females kept in seawater for 3 months became large and attained at the primary yolk globule stage, whereas oocytes of the females kept in seawater for one week were at the oil drop stage. Electron microscopic observation showed that gonadotrophs became active in the pituitary of females kept in seawater for 3 months. These results are the first findings showing that vitellogenesis is triggered under artificial rearing condition without any hormone treatments in cultured immature eels. These morphological results indicate that long term rearing in seawater induces vitellogenesis in the females, resulting in the shortened period for completion of vitellogeneisis by the injection of salmon pituitary extract.