耳鲍精子的超微结构

The ultrastructure of the spermatozoon of the ear abalone Haliotis asinina (Gastropoda: Haliotidae)

本文利用透射电子显微镜对耳鲍(Haliotis asinina Linnaeus)精子的形态及超微结构进行了研究。研究结果表明:耳鲍的精子由头部、中段和尾部三部分组成,全长41.6μm。精子头部长1.8μm,头部由顶体、顶体下腔和细胞核组成,顶体电子密度比较均匀,呈圆锥形,长0.6μm,基部宽度为0.65μm,占头部长的1/3;顶体下腔长0.03μm,宽为0.65μm,腔中含有中等电子密度物质;细胞核圆棒状,长1.17μm,核中部的宽度为1.0μm。精子中段较短,长0.51μm,宽1.2μm,主要由5个线粒体包围一对中心粒构成。尾部是一根鞭毛,从前到后逐渐变细,鞭毛是由细胞质膜包被的轴丝组成,轴丝为典型的“9+2”微管结构,即轴丝是由两个中心微管及均匀分布在中心微管周围的9对双联体微管组成。因此,耳鲍与其它鲍类精子的基本结构相似,形态结构的主要差异表现在三个方面:一是耳鲍精子的头部似圆锥形,长1.8μm,是目前已研究的鲍类中头部最短的种类;二是耳鲍精子顶体长比其基部宽要小,顶体电子密度比较均匀,顶体与核的电子密度差异不明显;三是耳鲍精子中段线粒体的数量为5个,没有发现6个线粒体现象的存在。

Spermatozoa of the ear abalone Haliotis asinina Linnaeus were examined using transmission electron microscopy. The results showed that the spermatozoa of H. asinina Linnaeus were structurally simple （classic ect-aqua sperm）. The total average length of each spermatozoan was 41.6μm. From anterior to posterior, the sperm consisted of three parts： the head, midpiece and end piece. The head consisted of a conical acrosome （0.6 μm in length, 0.65 μm in width, with a prominent subacrosomal cavity）, a barrel-shaped nucleus （1.17 μm in length, 1.0 μm in width, with a prominent frontier nuclear fossa and a posterior fossa） . The electron density of the acrosome was comparatively homogeneous. A short midpiece （0.51μm in length, 1.2 μm in width） consisted of a pair of orthogonally arranged centrioles surrounded by a five spherical mitochondria. The end piece was a 39.8μm long flagellum （with ＂9 ＋ 2＂ microtubular arrangement pattern axoneme） [ Acta Zoologica Sinica 53 （3） ： 552 - 556, 2007 ].