摘要:
生长在湖南地区水库环境的黄尾密鲴,雌、雄鱼性成熟一般为2冬龄。在具备繁殖条件的水库,其黄尾密鲴能自行产卵、受精、繁衍后代,不具备条件的,不能自然产卵,其卵母细胞只能发育到初级卵母细胞阶段(Ⅳ时相),而精细胞则能完成由精原细胞发育到精子的全部发育过程。冬季,达性成熟的黄尾密鲴,雌性卵巢为Ⅲ期,雄性精巢为Ⅳ期。每年的4月份,黄尾密鲴开始达人性腺成熟期,5月中旬至6月初为它的生殖盛期。初级卵母细胞由Ⅲ时相发育到Ⅳ时相基本是同步性的,卵巢成熟系数在一年中只出现1次高峰,经组织学研究与生产实践证明,黄尾密鲴系一年1次产卵类型。
Abstract:
The age at first maturity is 2 years for both male and female Xenocypris davidi in the reservoirs in Hunan. This species can reproduce naturally in the reservoirs with favourable conditions for spawning. However, in the reservoirs without favourable conditions, the fish fails to spawn. The oocytes can only develop to the primary stage (phase Ⅳ), though the spermatids can fully develop from spermatogonia to sperm. In winter, the ovaries of the mature female are at phase Ⅲ, and the testes of the male are at phase Ⅳ. The gonads start to ripen in April. The peak of spawning occures from mid May to early June. The development of primary oocytes from phase Ⅲ to phase Ⅳ is synchronous. The coefficient of maturition in the female shows only one peak in a year. Evidence from histology and from breeding practice led to the conclusion that this fish spawns only once in a year.
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