石鲽仔、幼鱼性腺发育的组织学观察

利用组织学方法对人工培育的石鲽(Kareius bicoloratusBasiewsky)仔、幼鱼性腺发育进行研究。结果表明,性腺的发育与体长密切相关。刚孵化石鲽的原生殖细胞数目为2个,孵化3 d数目增至8个,之后经过迁移,至孵化9 d到达生殖嵴。在全长为7.2～8.5 mm(孵化9～11 d)的仔鱼中,性腺原基中的体细胞迅速增殖并包围原生殖细胞,后者在全长10～15 mm(孵化后10～35 d)的仔幼鱼中增殖成为生殖干细胞。原始性腺在全长15～30 mm(孵化40～60 d)的幼鱼中逐渐发育完善,呈细线状,位于腹腔后部中肾管下方紧贴体壁。雌性性腺最早在全长32.5 mm(孵化66 d)的个体中出现分化特征,至全长89～102 mm时雌性性腺特征完全分化。雄性性腺的分化较雌性性腺晚,最早在全长为91 mm的幼鱼中开始,至全长为114～118 mm时雄性性腺分化特征已经十分明显。

Histological observation on gonadal development of fries and juveniles in Kareius bicoloratus Basiewsky

As a benthonic cold water fish,the stone flounder(Kareius bicoloratus Basiewsky) is an important cultured species in north China.In this study a histological process of gonadal development was investigated in K.bicoloratus fries and juveniles reared after hatchery,which was expected to provide helpful information on sex control during aquaculture.The results showed that gonad development was closely related to body length.In newly hatched fries primordial germ cells(PGCs) proliferated from 2 cells to 8 cells at 3-day-after-hatching(DAH),then migrated and reached the germinal ridge at 9 DAH.In fries at 7.2-8.5mm total length(TL)(9-11 DAH) the somatic cells proliferated rapidly and surrounded PGCs to organize the gonad rudiment,where PGCs proliferated and became germ stem cells in 10-15mm-TL individuals(10-35 DAH).Filamentous primordial gonad formed gradually in 15-30mm-TL juveniles(40-60 DAH),which was located in the posterior end of the abdominal cavity just beneath the mesonephric ducts closing to the body wall.Ovarian cavity,an early sign of female sex differentiation,was first observed in a 32.5mm-TL juvenile(66 DAH),and the ovarian characteristics were full possessed in 89-102mm-TL female juveniles.The differentiation of testis occurred in 91mm-TL juveniles and finished in 114-118mm-TL male juveniles,which was later than that of ovary.