中华锯齿米虾内外性征分化时间与特征

通过对中华锯齿米虾(Neocaridina denticulate sinensis)早期性腺发育的组织学观察和第一腹肢的形态学观察,研究了其雌雄性腺分化的时间、分化过程中生殖细胞及第一腹肢变化的特征。实验结果表明,卵原细胞出现在孵化后发育12～18 d的幼体,此时期所有幼体的第一腹肢内肢均具有刚毛。孵化后发育18～22 d幼体的性腺出现了两种类型:类型1和类型2,类型1具有典型的卵巢特征,之后沿着卵巢发育方向分化;类型2兼备精巢和卵巢的一些特征,之后沿着精巢发育方向分化。精巢的分化要经过一个类卵巢的阶段,在该时期还出现了雄性生殖肢,其第一腹肢内肢刚毛数量减少且为卵圆形,而雌性第一腹肢的内肢在形状与刚毛数量上无明显变化,雄性生殖肢的出现与精巢的分化时间是一致的。

The time and characteristics of internal and external sexual differentiation in the shrimp Neocaridina denticulata sinensis

Neocaridina denticulate sinenis larvae were collected regularly for histological investigation of the gonadal development characteristics and morphological observation of the first pair of pleopods’changes.The results showed that ovogoniums were forming and presented between 12 and 18 days post hatch(dph),and all specimens’ first pleopods were with many setae.18-22-dph was the critical time of the gonadal differentiation.There were two type gonads presenting in the period:type 1 and type 2.Type 1 had typical ovary characters and then developed into ovarian,The type 2 have some characters of ovaries and some characters of testis,but then developed into testis.In addition,the gonopod was presented in this period,the endopod of the first pleopod showed reduction and loss of the setae,while the female’s endopod of the first pleopod had no obvious changes,its appearance time was consistent with the testis formation time.