尼罗罗非鱼仔鱼个体发育及性腺分化的发育

Ontogenetic Development and Gonadal Differentiation and Development of Larvae Nile Tilapia (Oreochromis niloticus L.)

通过形态学、组织学的描述和显微结构的观察,研究了尼罗罗非鱼(Oreochromis niloticus)仔鱼在自然水温条件下(26～30℃)的个体发育和性腺分化发育过程。结果表明,仔鱼个体发育分为2个时期,仔鱼前期(从出膜到卵黄囊消失)和仔鱼后期(卵黄囊消失至奇鳍褶消失);性腺发育分化的时序为:5DPH时,开始出现生殖嵴;10DPH时,出现少数原始生殖细胞,形成原始性腺;28DPH时,可清晰辨认卵原细胞,呈现明显的性腺分化组织学特征,至42DPH时可辨认精原细胞。

Larvae of Nile tilapia （Oreochromis niloticus） were observed morphologically, histologically and micro- structurally under the natural condition with the temperature ranging from 26℃ to 28℃ in terms of ontogenetic de- velopment and gonadal differentiation and development. Observations showed that the development of larvae Nile tilapia can be divided into two stages： early larval stage from hatching to the complete yolk-sac absorption, and late larval stage from the complete yolk-sac absorption to the appearance of odd fin fold. The sex differentiation oc- curs at around 28 days post hatching （DPH）. The genital ridge, incomplete velum and enteron start to appear at 5 DPH. The primordial germ cells （PGCs） appear at 10 DPH although few, and form primordial gonad. The ooeytes can be easily distinguished at 28 DPH and show clear histological characteristics of gonadal differentiation. The spermatogonia can be distinguished at 42 DPH.