The testis development and sperm ultrastructure ofAurelia aurita medusae were studied with paraffin wax slice and histological staining,scanning and transmission electron microscopy techniques.The testis development could be divided into four stages,including proliferating,growing,maturing,and spawning,according to the histological character.The horseshoe-like gonads are filled with many follicles,and wrapped with outer membranes.After sexual maturity of medusae,the follicle would be full of sperms in the cavity,and then release mature sperms.The primitive matured sperm is about 33.62 μm in total length,including head,middle piece,and tail.The head is long-and-pointed chili-shaped and composed of acrosome and nucleus.Between plasma membrane and nucleolus membrane is a gap full of cytoplasm.The middle part includes centriolar complex and mitochondrias,and they are in sleeve structure.The basal body stands orthogonally to the proximal centriole in parallel to the long axis of spermatozoon.Frequently,four spherical mitochondrias lined up in a loop.The endomembrane of the sheath is fused with plasma memebrane of flagellum.The tail is a whip-like flagellum,consisted of axoneme in typical "9+2" microtubular structure,and surrounded by plasma membrane.%采用组织切片、扫描电镜和透射电镜技术研究了海月水母(Aurelia aurita)精巢发育过程及精子显微结构.结果表明:(1)海月水母精巢发育分为四个阶段,即增殖期、生长期、成熟期和排放期;海月水母精巢位于马蹄形胃腔内部,由两层外膜包裹的大量长圆形滤泡组成,性成熟后,滤泡内部充满精子,之后成熟精子汇集于滤泡腔排出体外.(2)海月水母精子全长约33.62μm,为原生型精子;精子头部呈长尖辣椒状,具顶体,核膜与质膜空隙较大,充满细胞质;精子中部主要由中心粒复合体和线粒体组成,且具有袖套结构,袖套内膜与鞭毛质膜相互融合,近端中心粒与基体垂直排列,基体的长轴与精子长轴平行,向后延伸形成尾部轴丝,线粒体以4个居多,呈圆环状排列,线粒体脊较明显;精子尾部细长,由质膜和轴丝组成,轴丝横切面为典型的“9+2”结构.
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