本文利用组织切片的方法研究了双单倍体牙鲆的性腺发生、性别分化及早期发育。结果显示：双单倍体牙鲆中除雌性外，还有雄性和未分化鱼出现，所占比例分别为56 %、38 %和6 %。双单倍体牙鲆雌性的性别分化晚于普通牙鲆。雌鱼至100 日龄，卵巢腔仍未闭合；110 日龄雌鱼的产卵板上存在大量向卵母过渡的卵原细胞，未见Ⅰ时相卵母细胞出现。双单倍体牙鲆雄鱼精巢的分化在时间上和普通牙鲆的基本相同。随着发育的进行，双单倍体牙鲆雌鱼的卵巢出现部分异常的卵母细胞以及卵巢退化现象；部分雄鱼的精巢也有退化现象出现。9~11 月龄，双单倍体牙鲆雄鱼的精巢发育到Ⅲ期，而普通牙鲆性腺在同期进入了Ⅳ期；11 月龄开始双单倍体牙鲆雄鱼精巢有退化的迹象；13~15 月龄，精巢退化成精小叶，其中只含有精原细胞，初级精母细胞消失不见，似Ⅱ期精巢。

We studied the gonadogenesis, gender differentiation and early stage development of doubled haploid Japanese flounder (Paralichthys olivaceus) by using histological sections. The results indicated that there were some female, male and also undifferentiated individuals in the doubled haploid population, and the ratio was 56%: 38%: 6%. The gender differentiation in female doubled haploid was later than the normal one. At 100 days, the ovarian cavity was still not closed; and at 110 days, there were a large number of transitional cells from oogonium to oocyte on the spawning board, and the stageⅠoocyte was not observed. For the male double haploid, the gender differentiation was basically the same in time with the normal one. With the development of gonad, there were some abnormal oocytes in the ovaries of double haploids, and some ovaries degenerated. There were also some degeneration appeared in the testes of male doubled haploids. At 9-11 months old, the testis of doubled haploid was at stage Ⅲ, while the testis of normal Japanese flounder develop into stage Ⅳ. From 11 months, the testes of some doubled haploid begun to degenerate. At 13-15 months old, there were only spermatogonium in the seminiferous lobules, and the primary spermatocyte disappeared, like the testis in stageⅡ.