瘤头鸭精子的超微结构

瘤头鸭精子分为头部和尾部。头部包括顶体和细胞核。顶体位于最前方。顶体下腔中有顶体突起。细胞核棒状,位于顶体之后。尾部由颈段、中段、主段和末段构成。颈段含有近端中心粒和远端中心粒。近端中心粒位于核后端的植入窝中。远端中心粒紧随其后。中心粒的外方有线粒体鞘。中段的中央结构是前轴丝(轴丝的前体),它与前方的远端中心粒相连。前轴丝的外方也有线粒体鞘。主段的中央结构是轴丝,它接于前轴丝的后端。轴丝外方有一圆筒状鞘。末段只有轴丝而无圆筒状鞘。整条精子外方包有细胞质膜。

The Ultrastructure of Spermatozoa of Muscovy Drakes

The spermatozoa of Muscovy Drakes consist of two parts ~head and tail. The anterior part of the head is a cone-shaped acrosome. Under the acrosome is a subacrosome space with a stick-shaped acrosomal spine in it. The base of acrosomal spine protrudes into the nuclear pocket. Beyond the acrosome is a rod-shaped nucleus. From our observation, the tail consists of neck region, middle piece, principal piece and end piece. The neck region contains the proximal centriole and the distal centriole. The proximal centriole is in the implantation fossa and followed by the distal centriole. From the anterior part to the posterior part, the strueture of the distal centriole changes egularly. The middle piece possesses a precursor of axoneme. The precursor of axoneme is derived from the distal centriole. A mitochondrion sheath encircles both the centrioles and the precursor of axoneme. At the principal piece the central structure is axoneme which is connected with the precursor of axoneme. The axoneme is enclosed by a cylindrical sheath. At the end piece there is no sheath but only axoneme.