水温对半滑舌鳎性腺组织发育的影响

探讨了不同温度(19,21,23,25和27 ℃)对半滑舌鳎的性腺组织发育的影响。在受精后39～106 d对半滑舌鳎进行温度控制处理,通过石蜡组织切片,对半滑舌鳎早期性腺分化发育进行组织学观察。发现在19 ℃饲养条件下,受精后46 d(pfd46)半滑舌鳎性腺原始生殖细胞数量增加,有分化成卵巢的倾向;在该条件下,pfd82半滑舌鳎性腺开始分化为精巢。pfd82时,27 ℃条件下的幼鱼卵巢中卵原细胞数目大量增殖;精巢中精小叶多而密,结缔组织间隔清晰。pfd129时,27 ℃处理的幼鱼卵巢发育到Ⅱ期,其他温度处理组仍处于Ⅰ期卵巢,但随着温度的提高,卵巢中卵母细胞数目增多,且由散乱分布变为有序的排列在卵巢小叶中;精巢中贮精囊数量增多,囊腔中精子增多。pfd142时,高温处理组幼鱼性腺发育最快,其Ⅱ期卵巢中卵母细胞数目最多,精巢中后期生精细胞偏多,精子几乎分布到各个精小叶中,且贮精囊结构发达,内纳高密度精子,在周围输精管中也分布着精子。结果表明，温度影响了半滑舌鳎性腺发育程度,二者呈现线性关系,在适当温度范围内,性腺发育速度随着温度升高而加快。

Effect of water temperature on gonadal development in half smooth tongue sole(Cynoglossus semilaevis G?nther)

Although females grow 4-6 times faster and reach larger adult sizes than males in half-smooth tongue-sole,Cynoglossus semilaevis,male ratio is higher than female study culture conditions.Thus,it is necessary for us to make a detailed understanding of gonadal development,which provides a theoretical basis for sex control.What’s more,water temperature is considered a very important modulator of reproductive activity in fish.Therefore,the principal purpose of the present work is to analyze the effects of different temperatures(19,21,23,25 and 27 ℃)on gonadal development in the half-smooth tongue-sole,which were reared for 67 days from 39 to 106 days post fertilization(pfd).And the temporal dynamics of germ cell growth and gonad development were examined during the experiment using light microscopy method.We found that the histological differentiation occurred firstly on pfd46 in the half-smooth tongue-sole reared at 19 ℃,as the gonad with the increasing primordial germ cells(PGCs)will develop into ovary.And the gonad without cavity will develop into testis in fish held at 19 ℃ on pfd82.At the same time,compared with fish kept at other temperatures,half-smooth tongue-soles maintained at 27 ℃ demonstrated increased oogonium proliferation in females and the spermatocyst size in males.And the ovaries of the fish reared at 27 ℃ were in stage Ⅱ on pfd129.Higher water temperatures triggered rapid germ cell differentiation and seminal vesicle growth,and relatively,lower water temperatures delayed,hence,not until pfd142,the ovaries of juvenile feeding at 23 ℃ and 25 ℃ were in stageⅡ.In addition,under higher temperature treatment,there were more oocytes in the ovarian lamella;in males,late-stage testis germ cells were predominated at this time,Especially in the juveniles rearing at 25 ℃,spermatozoa were distributed to almost all seminal lobules,even seminal vesicles and sperm ducts were filled with high density spermatozoa.All of these results suggest that higher water temperature favors gonadal development.