【作者】 刘蔓；

【导师】 韩英；

【作者基本信息】 东北农业大学 ， 动物遗传育种与繁殖， 2009， 硕士

【摘要】 虹鳟肉质鲜美、营养丰富,是世界粮农组织向全球推荐养殖的三种养殖鱼类之一,也是我国重要的冷水性养殖鱼类。由于多倍体诱导技术在鱼类育种领域得到广泛应用,人工诱导虹鳟多倍体也已获得成功。三倍体雌性虹鳟性腺不发育,因此比二倍体具有更强的生长优势和群体产量。近年来养殖人工诱导三倍体不育系虹鳟已进入商品化生产。由于三倍体制种的需要,四倍体虹鳟也被成功诱导。试验以二倍体、三倍体和四倍体雄性成熟虹鳟为材料,采用组织学、扫描电镜、透射电镜技术对其精巢结构和精子发生进行了比较研究。并对三倍体虹鳟精子发生中的败育现象、精子的倍性、精子形成机制等进行了深入的探讨。试验结果表明:1.虹鳟精巢属于典型的壶腹型,精巢由外膜和实质两部分组成,从外膜上伸出隔膜,将整个精巢分割成圆形或长圆形的壶腹(精小叶),这些壶腹不规则地占满整个精巢的内部。隔膜中有血管,通过血液循环来传递营养物质和激素,促进精子发生。在精巢发育过程中每个精小叶又形成许多精小囊,精子在精小囊中形成,随着精子的成熟精小囊破裂,精子汇聚于小叶腔,最后进入精巢腹部的输精管。三倍体虹鳟精子数量较二倍体少,各精小叶间充斥着大量染色较浅的结缔组织,精小叶中出现坏死区,染色较深,坏死细胞呈粘连状,这些坏死细胞大都为败育的精子细胞。2.二倍体、三倍体和四倍体虹鳟精子发生均经历精原细胞、初级精母细胞、次级精母细胞、精子细胞过程,最后变态为成熟精子。不同倍性虹鳟各期生精细胞除体积不同外,其超微结构基本相同。3.三倍体虹鳟在精子发生过程中生殖细胞败育现象始终存在,表现出各种畸形,如精母细胞液化、分裂异常,许多精子细胞趋于解体,不能形成结构正常的成熟精子等。败育现象在精子细胞变态期尤为明显。4.二倍体虹鳟精子头部大小较一致,体积为3.36±0.19μm3。三倍体虹鳟精子有大、中、小三种类型,小型精子体积(3.51±0.17μm3)与二倍体虹鳟精子大小相似,占精子量的29.4%;中型精子体积为5.22±0.21μm3,是单倍体精子体积的1.56倍,占精子量的58.8%;大型精子体积为6.87±0.19μm3,是单倍体精子体积的2.08倍,占精子量的11.8%。由此推测,三倍体虹鳟精子倍性存在n型、1.5n型和2n型。四倍体虹鳟能顺利完成精子的发生,其精子大小一致,精子头部细胞核直径为2.82±0.17μm。5.基于三倍体虹鳟存在n型、1.5n型和2n型精子,推测三倍体虹鳟大部分精母细胞能够像二倍体一样完成减数分裂,形成1.5n型的精子;一部分精母细胞染色体发生了不等分裂,形成了60个二价体和60个单价体,即形成n型和2n型精子;另一部分精母细胞染色体联会紊乱,无法完成减数分裂,最终坏死。6.在三倍体虹鳟精巢中支持细胞对生殖细胞起着支持、固定和输送营养的作用,同时具有分泌功能。在败育生殖细胞周围的支持细胞异常发达,在胞质中有较多的囊泡和溶酶体能吞噬败育的生精细胞。更多还原

【Abstract】 Because of the tasty meat and rich nutrition, rainbow trout had become one of three recommended cultural fish by the world food and farming organization, and aslo the important cold-water cultivated fish in china. Since polyploid induction technique has become widespread, especially in rainbow trout artifical-induced polyploidy fish had been successfully produced. Female triploid rainbow trout had a much stronger growth advantage and population yields owning to the agenesis of gonad compared with the diploid conterparts. Recently, artifical-induced triploid sterile lines had become commercial used. In accordance with the production of triploid fish, tetraploid rainbow trout had been successful induced.Our experiments were carried out used the different polidy rainbow trout (diploid, triploid, tetraploid) as materials, and comparative studies about the the structure of spermary and spermatogenesis of them followed the methods of histology, scanning electron microscope, transmission electron microscope. And further discussed the phenomenon of abortion, ploidy of spermatozoon, mechanisms of spermiogenesis of triploid rainbow trout during the process of spermiogenesis.The results showed that :1. Rainbow trout was typically ampulla type spermary, spermary was consisted of two parts which was outer membrance and substance part, septum was streched out from outer membrance and divided the spermary into round or long circular pars ampullaris (testicular lobules), and this pars ampullaris was full of the inside of spermary irregularly. Septum had blood vessel which could transfer nutrition and hormone through blood circulation to promote the genesis of sperm. Every testicular lobule could form spermatogonial cysts in which sperm was produced. As the maturation of sperm, spermatogonial cysts was rupture and sperm was released and converged with the lumen of lobule, at last got into the spermatic duct. Triploid male rainbow trout had fewer sperm than diploid conterparts, and the interval of lobule was filled with bulks of light-stained connective tissues, zone of necrosis emerged in lobule and was dark-stained, cells of necrosis adherenced together and were mostly abortive spermatid.2. Spermatogenesis of different ploidy rainbow trout (diploid, triploid, tetraploid) had all undergone spermatogonium, primary spermatocyte, secondary, spermatocyte, spermatid, and finally transformed into sperm. Ultrastructural organization of spermatogenic cells of different ploidy rainbow trout was the same on the whole besides the differences of volume.3. Abortion of reproductive cell of triploid rainbow trout during spermatogenesis was existed all the time, and showed various kinds of abnormity, such as the liquefaction of spermatocyte, abnormality meiosis, many spermatid tend to be disintegrate, unable to from normal sperm etc. And this phenomenon was especially obvious during the stage of spermatid metamorphosis.4. Heads of diploid rainbow trout were uniform at the size, and the volume was 3.36±0.19μm3. While,sperm of triploid rainbow trout had three types of big,middle and small, the small type of sperm accounted 29.4% of total sperm and resembled diploid rainbow trout at the volume (3.51±0.17μm3); middle type sperm with the volume (5.22±0.21μm3) of 1.56 times of haploid sperm accounted 58.8% of total sperm; big type sperm with the volume (6.87±0.19μm3) of 2.08 times of haploid sperm accounted 11.8% of total sperm. We could infer from this, the sperm of triploid rainbow trout existed three types of n type, 1.5n type and 2n type. Teraploid rainbow trout could finish spermatogenesis smoothly, the size of sperm was uniform and diameter of nucleus of head was 2.82±0.17μm.5. Based on triploid rainbow trout had n type, 1.5n type and 2n type. Sperm, we could specula- te that most spermatocyte of triploid rainbow trout could finish meiosis and form 1.5n type sperm; parts of spermatocyte undergo disparity division, forming sixty bivalent and sixty univalent, that is n type and 2n type sperm. another parts of spermatocyte happened derangement of synapsis, could not finish meiosis and ultimitaly leaded to cellular necrosis.6. Sertoli cell plays as a role of supporting, fixing and conveying nutrition for reproductive cell in spermary of triploid rainbow trout, and similarly had the function of secretion. Sertoli cells surounded the abortive reproductive cells were hypertrophy, and cytoplasm of them had many lysosomes which could phagocytize abortive spermatogenic cells.更多还原