香鱼卵巢发育的组织学研究

A HISTOLOGICAL STUDY ON THE DEVELOPMENT OF OVARY OF AYU

本文根据在天然水域中各个不同发育阶段香鱼卵巢的组织学观察资料,对香鱼卵膜结构、第2时相卵母细胞中出现的透明层、核仁排出物在卵黄形成中的作用以及受精孔形态等问题作了描述和探讨。并对香鱼性周期内卵巢发育和产卵类型等问题作了说明。

A histological study on the development of the ovary of Ayu, Plecoglossus altivelis was carried out through the years from 1979 to 1980. All the fish were sampled fromthe river 'Wu Qi' in Zhejiang province. From December to April, the gonad has not yet differentiated; duringMay to August the ovary enters into stage Ⅱ; From early September to middle Sep-tember, the ovary develops into stage Ⅲ; from middle september to early October itenters stage Ⅳ. The spawning season of Ayu is in October-November the ovaryreached to stage Ⅴ, and the oocytes is mainly in phase 5, but also contains the phase4,3,2 and 1. After the releasing of one bateh of eggs, the spent ovary is observed tobe in state Ⅵ-Ⅳ, the oocytes are mainly in phase 4 and empty follicles, then theovary develops again into stage Ⅴ' and the next spawning takes place. The ovarydevelops to stage Ⅴ once again. Evidently the development of the oocytes in the ovaryof Ayu is in successive processes and the female releases eggs 3-4 times in onespawning season. In the stage Ⅱ of the development of oocytes, the nucleolus containing substancewhich is possibly related to the fomation of yolk within the oocyte, enters into cyto-palsm by the part rupture of the nuclear membrane. In the middle stage of phase 2, there is a transparent layer surrounding thenucleus. Egg membrane of Ayu is composed of 3 layers: plasma membrane, zona radiataand attachment membrane which is present in the oocyte in phase 3. A syncytium is conical in shape and located near the fertilization orifice consistingof more than 10 cells.