疣吻沙蚕(Tylorrhynchus heterochaetus)成熟精子及卵子的超微结构观察

Ultrastructural observation of mature sperm and ovum of Tylorrhynchus heterochaetus

【目的】探明疣吻沙蚕成熟精子及卵子的超微结构特征,为其繁殖生物学的基础研究提供依据。【方法】利用扫描电镜和透射电镜观察疣吻沙蚕成熟精子及卵子的超微结构。【结果】疣吻沙蚕精子全长为(39.80±1.24)μm,由头部、中段、尾部3个部分构成。精子头部主要由顶体和细胞核组成,顶体呈倒“U”形,细胞核为卵圆形。中段较粗,与头部紧紧相连,主要由中心粒和线粒体等构成。线粒体位于宽大的核膜中,围绕在远端中心粒周围,形状为卵圆形,透射电镜下可观测到5个线粒体。尾部为细长鞭毛,轴丝为典型“9+2”结构,外侧有波浪形侧鳍。成熟卵子呈卵圆形或近圆形,直径为(140.63±2.09)μm,透射电镜下可见明显的细胞核,核内有核仁,成熟的卵黄颗粒电子密度深且均匀,卵黄颗粒周围存在大量的脂滴。【结论】明确了疣吻沙蚕成熟精子及卵子的超微结构特征,为理解其生殖细胞发育、受精机制提供了重要的形态学基础。

【Objective】The ultrastructural characteristics of mature sperm and ovum of Tylorrhynchus heterochaetus were explored to provide basis for its reproductive biology.【Method】The ultrastructure of mature sperm and ovum of T.heterochaetus were observed with scanning electron microscopy and transmission electron microscopy.【Result】The sperms were approximately(39.80±1.24)μm in length,made up by 3 parts of head,middle section and tail.The sperm head was primarily comprised of acrosome with inverted“U”shape and oval nucleus.The middle section,closely connected to the head,was thick and mainly composed of centriole and oval-shaped mitochondria.The 5 observable mitochondria were located in the wide nuclear membrane around the distal centriole.The tail was a slender flagellum,featuring a typical“9+2”axoneme structure with wavy lateral fins on the exterior.The mature ova were oval or nearly round,with a diameter of(140.63±2.09)μm and distinct nucleus and nucleolus under transmission electron microscopy.The electron density of mature yolk granules was deep and uniform,with numerous lipid droplets surrounding the yolk granules.【Conclusion】The ultrastructural characteristics of mature sperm and ovum of T.heterochaetus were elucidated,which provided an important morphological basis for research on their development and fertilization mechanism.