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1.
用扫描和透射电子显微镜研究了尼罗河鲶——盾头歧须鮠(Synodontis schall)的精子发生和精子的超微结构。精巢中含有无数肾形的生精小叶,我们将其称为"精原无限型"。尽管其精子发生的大体过程与同类鱼无异。但是,在细节上仍具其独特之处。这些特点未见在其他硬骨鱼中报道过。其特点主要是:生精过程中不发生细胞核的旋转,中心粒复合体和轴丝起始段直接发生在核的基底面垂直线上,有无数的粗的固定纤维将近端中心粒和远端中心粒的近侧部连接到细胞核上。另外,精子发生过程中还包括染色质浓缩,细胞质和线粒体向细胞核的尾端迁移,在核的后端中轴位置上形成中等大小的核后凹,近端中心粒和远端中心粒的一部分嵌在核后凹之内,短的胞质内陷管将线粒体与鞭毛分隔开。精子头部接近圆形,无顶体或顶体泡,鞭毛的中段及胞质内陷管均较短,整个鞭毛却很长,鞭毛侧面无翼膜,轴丝呈典型的9 2结构。上述结果显示,盾头歧须鮠的精子发生具有类型Ⅰ和类型Ⅱ的共同派生特征,这种特征在常见的其他硬骨鱼中也是常有的。但是,正如文献所报道过的另两种尼罗河鲶——金鯵(Chrysichthys auratus)和电鲶(Malapterurus electricus)中的情况一样,盾头歧须的精子发生与类型Ⅲ的精子发生过程更为相似。  相似文献   

2.
超微结构研究显示傅氏凤尾蕨(Pteris fauriei Hieron)精子发生过程包括生毛体、多层结构和鞭毛等运动细胞器重新发生,环状线粒体形成,核塑形等过程,最后形成一个螺旋形的游动精子,这与其他真蕨类精子发生过程相似。本研究观察到的一些新现象包括:精细胞在分化早期呈极性,细胞核位于精细胞的近极端,生毛体、线粒体和质体等细胞器主要分布远极端;在生毛体分化早期,可见大量微管从其发出,其周围线粒体丰富;基体分化经历了前中心粒、中心粒和基体3个阶段,它们的内部结构不同;研究表明生毛体内的不定形物质是微管组织者,多层结构、附属微管带及鞭毛等细胞器均由不定形物质分化形成;精细胞在分化过程中产生了丰富的膜结构,它们可能为精核塑形提供原料。本研究报道了傅氏凤尾蕨精细胞分化的一些细节,这有助于进一步揭示蕨类植物精子发生的细胞学机制。  相似文献   

3.
中国淡水蛏精子发生的超微结构研究   总被引:13,自引:3,他引:10  
利用透射电镜观察了中国淡水蛏的精子发生和精子结构。描述了精子发生过程中各细胞形态结构的变化;揭示了细胞核、线粒体和项体等的演变过程。中国淡水蛏的精子经过精原细胞、初级精母细胞、次级精母细胞和精子细胞,最终限育为成熟的精子。精子为典型的原生型,由头部、中段和尾部构成。项体复合体位于精子头部前端,呈“⊥”形,精核近圆形;中段包括2个中心粒和4或5个紧密排列的椭圆形线粒体;尾部鞭毛断面为典型的“9+2”  相似文献   

4.
三疣梭子蟹精子的发生及超微结构研究   总被引:28,自引:9,他引:28  
李太武 《动物学报》1995,41(1):41-47
用透射电镜观察三疣梭子蟹的精子发生过程及精子的超微结构。发现精原细胞较大,卵圆形。核大而圆,染色质分散,附着于核膜之内侧。胞质少,内含线粒体和粗面内质网等结构。初级精母细胞比精原细胞略小,卵圆形,核内染色质凝聚成团块,散布于核质中,除线粒体外,胞质中尚含有很多内质网小泡和游离核糖体。次级精母细胞多边形,核卵圆形,染色质致密,线粒体等含量均下降。早期精细胞质中由内质网产生许多颗粒,这些颗粒合并成为大  相似文献   

5.
东方扁虾精子发生的超微结构   总被引:2,自引:0,他引:2  
应用电镜技术研究了东方扁虾(Thenus orientalis)精子发生的全过程,精原细胞呈椭圆形,其染色质分布较均匀,线粒体集中于细胞一端形成“线粒体区”。初级精母细胞较大,染色质凝聚成块,次级精母细胞核质间常出现大的囊泡,胞质内囊泡丰富而线粒体数量却明显减少,早期精细胞核发生极化、解聚,部分胞质被抛弃。中期精细胞外观呈金字塔形,分为三区;正在形成的顶体位于塔顶,核位于塔基部,居间的细胞质基质内富含膜复合物,后期精细胞顶体进一步分化。形成顶体帽和内、外顶体物质等三个结构组份。成熟精子核呈盘状或碗状,具有5-6条内部充满微管的辐射臂。  相似文献   

6.
日本鳗鲡精子形成过程中的形态结构特点   总被引:1,自引:0,他引:1  
本文通过扫描电镜、透射电镜观察了日本鳗鲡(Anguilla japonica)精子形成的特殊过程及产生细胞器的特殊结构。由精细胞变成精子包括四个特殊阶段,即经过早期、中期、晚期和精子期.最后形成正常成熟的精子.(1)早期阶段:其特征是细胞核由椭圆形逐步变成长条形;在细胞核的一端.有一个大的圆的染色较浅的形状似球形的特殊结构,约占细胞核的三分之一,其内含有少量着色深的颗粒状和线条状物质,外面由质膜包被着与细胞核分开,该结构和细胞核的外层还有一层质膜包着形成一个整体:精子早期阶段没有形成独立的线粒体和中心粒。(2)中期阶段:其特征是细胞核呈长条形.有球形结构的一端成为细胞核的上端,无球形结构的一端成为细胞核的下端,在下端出现鞭毛的原基;球形结构伴随着精子的发生也发生变化,内部逐步分化出中心粒和线粒体等细胞器:在细胞核的中段有明显的溶酶体分布。(3)晚期阶段:其特征是细胞核呈“眉形”或“新月形”.中心粒从球形结构中释放出来形成独立结构.球形结构中只剩下还没有形成独立结构的线粒体:在细胞核的下端鞭毛的原基处长出较长的鞭毛,这时期的精子已具有运动能力。(4)精子期:其特征是细胞核呈圆形,中心粒位于植入窝内,线粒体分布在细胞核的下面.在线粒体的下面有袖套腔形成,此时形成的鞭毛为“9+2”结构。日本鳗鲡精子经过四个时期的变态.才能形成真正成熟的精子。  相似文献   

7.
通过透射和扫描电镜观察了白肛海地瓜(Acaudina leucoprocta)的精子发生过程及其形态结构,揭示了白肛海地瓜精子发生时期一系列变化,其精子发生分为精原细胞、初级精母细胞、次级精母细胞、精细胞、成熟精子5个时期。精原细胞体积最大。精母细胞染色质开始凝集。精细胞前顶体颗粒形成。白肛海地瓜成熟精子的超微结构为原生型,由头部、中部、尾部组成,头部圆形,最前端为顶体,核染色质凝集成团块状,中部是线粒体和中心粒复合体融合成1个超大结构,尾部长约60μm,尾部鞭毛横切面为典型的"9+2"型结构。  相似文献   

8.
大黄鱼的精子发生   总被引:17,自引:0,他引:17       下载免费PDF全文
应用电子显微镜技术观察了大黄鱼(Pseudosciaena crcea)的精子发生过程。其发生经历了初级精原细胞、次级精原细胞、初级精母细胞、次级精母细胞和精子细胞阶段,精子细胞再经过精子形成过程成为精子。在精原细胞阶段,部分核仁物质排出核外,成为拟染色体。拟染色体的主要成分是核糖体。在精子发生中,拟染色体逐渐扩散到生精细胞的胞质中。成熟分裂的前期Ⅰ,同源染色体经历了联会复合体形成和解体的变化。在精子形成过程中,精子细胞先形成鞭毛,随后细胞核逐渐浓缩。  相似文献   

9.
菲律宾蛤仔的精子发生和精子超微结构   总被引:12,自引:0,他引:12  
用透射电镜研究了菲律宾蛤仔(Ruditapes philippinarum)精子结构和精子发生过程中细胞形态结构的变化及细胞器的演变规律。菲律宾蛤仔雄性生殖细胞的形态由椭圆形渐变为辣椒状,细胞核的形态由椭圆形逐渐拉长,渐变为锥形。染色质的凝集经历:小颗粒团块状一较大颗粒均匀状一粗颗粒均匀状的过程。线粒体在演化过程中数量先增多后逐渐减少,嵴数逐渐增多,电子密度和体积逐渐增大。高尔基体在初级精母细胞期已经发育,随后的各期中发育良好,分泌旺盛。精细胞Ⅱ期,高尔基体分泌的潴泡开始融合,形成前顶体囊。精细胞Ⅲ期,高尔基体的分泌物仍不断融合。精细胞分化的后期,前顶体囊逐渐发育形成顶体。菲律宾蛤仔成熟精子呈长辣椒状,为原生型,由头部、中段和尾部构成。头部的顶体为细长柱形,末端渐细,电子密度较小;细胞核为锥形;中段线粒体4个,尾部鞭毛为典型的“9 2”型结构。此外在成熟精子线粒体环横切面有一特殊“风车状”结构。  相似文献   

10.
日本沼虾精子发生的研究   总被引:18,自引:3,他引:18  
赵云龙  堵南山 《动物学报》1997,43(3):243-248
对日本沼虾精子发生全过程的电镜观察表明:精原细胞核染色质分散,胞质内有线粒休、内质网的分布。初级精母细胞核染色质块状,不均匀地分布于核中,内质同多小泡多。次级精母细胞核染色质大多分布于核膜内侧,内质网聚集成团,精细胞分化形成精子的早期,胞核增大,核侧形成内质同多小泡的聚合体;中期的核内染色质浓缩,同时形成空囊状结构,  相似文献   

11.
The general organization of the male genital system, the spermatogenesis and the sperm structure of the proturan Acerella muscorum have been described. At the apex of testis apical huge cells are present; their cytoplasm contains a conventional centriole, a large amount of dense material and several less electron-dense masses surrounded by mitochondria. Spermatocytes have normal centrioles and are interconnected by cytoplasmic bridges. Such bridges seem to be absent between spermatid cells and justify the lack of synchronization of cell maturation. Spermatids are almost globular cells with a spheroidal nucleus and a large mass of dense material corresponding to the centriole adjunct. Within this mass a centriole is preserved. Mitochondria of normal structure are located between the nucleus and the plasma membrane. The spermatids are surrounded by a thick membrane. No flagellar structure is formed. Sperm have a compact spheroidal nucleus, a large cap of centriole adjunct material within which a centriole is still visible. A layer of mitochondria is located over the nucleus. The cytoplasm is reduced in comparison to spermatids; many dense bodies are interspersed with sperm in the testicular lumen. The sperm are small, immotile cells of about 2.5-3 μm in diameter.  相似文献   

12.
三角帆蚌精子的发生   总被引:7,自引:1,他引:7  
报道了光镜和透射电镜下三角帆蚌精子的发生过程及其一系列重要的形态变化。包括核延长,染色质浓缩,线粒体逐渐融合并后移;胞质减少及鞭毛形成,精原细胞是精巢中体积最大的细胞,细胞膜界限不明显,内质网发达,精母细胞开始出现中心粒,精细胞分化可分为3个阶段。成熟精子属原生型,由头部、中段和尾部三部分组成。  相似文献   

13.
褶纹冠蚌外套膜组织培养的分泌物的偏光显微镜观察   总被引:3,自引:0,他引:3  
以淡水育珠贝中珍珠形成较快的褶纹冠蚌为材料,用相差显微镜观察组织培养的外套膜的分泌物的形成和变化,用偏光显微镜观察分泌物的双折射现象,并与活体外套膜的分泌物、贝壳的角质层、棱柱层、珍珠层的双折射现象进行比较。结果表明;离体培养的外套膜细胞不仅能产生活体细胞相同的分泌物,而且分泌物还能在培养过程中形成结晶,并逐渐生长。发现外套膜的不同部位分区培养所形成的分泌物的性状与结晶性质和活体有一致性,表明组织培养的外套膜小片具有贝体原来的组织结构、分化特征和分泌功能。  相似文献   

14.
Spermatozoids of the siphonous green alga Dichotomosiphon tuberosus (A. Br.) Ernst are specialized gametes which differ in many respects from other green algal motile cells, but whose microanatomy nevertheless indicates its chlorophycean affinities. Each cell is anteriorly biflagellate and contains an irregularly shaped nucleus attached to the flagellar bases by a complex support apparatus. There is a single reduced chloroplast in each spermatozoid and numerous (50–100) minute spherical mitochondria, only 0.3 μm diam. These move vigorously in the living cell and when viewed with the light microscope they bear a striking resemblance to bacteria. Rather unexpectedly, no contractile vacuoles could be detected, even though the gametes are naked freshwater cells. Daring spermatogenesis the nucleoli of the vegetative cells disperse and are replaced by a large dense body presumably formed from either nucleolar material or condensed chromatin. The flagellar apparatus includes a cruciate flagellar root system, a feature now known to be characteristic of most green algae, exceptions being those putative ancestors of the higher plants and bryophytes. Discharge of spermatozoids from the antheridia is extremely rapid and the whole process may be finished in 30 sec. The antheridium lacks a pore apparatus, but at maturity bursts open explosively at the apex. Phyletic affinities are discussed and it is concluded that the ultrastructure of the motile cells does not, at this time, support the separation of the siphonous green algae from other green algae into a separate class.  相似文献   

15.
泥螺精子发生的超微结构研究   总被引:10,自引:0,他引:10       下载免费PDF全文
利用透岸民镜观察了泥螺精子发生的过程。结果表明;泥螺精子发生经历了一系列重要的形态和结构变化,主要有核逐渐延长,染色质浓缩,顶体形成,线粒体逐步发达与融合,胞质消除及鞭毛的形成等。泥螺精细胞分化可分为3个时期,在精细细胞分化过程中,细胞核形态及染色质的变化与其他软体动物有较大的差异,核内椭圆形到肾形,再变化为长圆柱形;染色质由絮状颗粒变为细纤维丝状,再变为长纤维丝状,最后向高电子密度均质状态转变,初步探讨了泥螺精子发生过程中核及细胞器的超微结构变化在分类上的意义。  相似文献   

16.
This paper reports an electron microscope study of typical and atypical spermatogenesis in the pond snail, Cipangopaludina malteata. In the typical spermatid the nucleus undergoes profound changes as development proceeds, affecting both its form and internal fine structure. A large number of roughly parallel, dense filaments, arranged along the long axis of the nucleus, fuse with each other to form in the end the homogeneous helical body characteristic of the head of the adult spermatozoa. The nebenkern is apparently mitochondrial in nature and, in its early development, is similar to that of insects except that it appears as a double structure from the beginning. As differentiation proceeds, the mitochondria lose their membranes, and the residual, now denuded cristae, reorganize to give a parallel radial arrangement. In the last stages of development, the nebenkern derivations become applied to the sheath of the middle piece in a compact helical fashion. In the development of the atypical spermatozoa, the nucleus fails to differentiate and simply shrinks in volume until only a remnant, devoid of DNA, is left. The cytoplasm shows numerous vesicles containing small Feulgen-positive bodies, 80 to 130 mmicro in diameter. These vesicles plus contents increase in number as spermatogenesis proceeds. The "head" structure of the atypical spermatozoa consists of a bundle (7 to 17) of tail flagella, each with a centriole at its anterior end. The end-piece of the atypical form appears brush-like and is made up of the free ends of the several flagella.  相似文献   

17.
This paper reports an electron microscope study of typical and atypical spermatogenesis in the pond snail, Cipangopaludina malteata. In the typical spermatid the nucleus undergoes profound changes as development proceeds, affecting both its form and internal fine structure. A large number of roughly parallel, dense filaments, arranged along the long axis of the nucleus, fuse with each other to form in the end the homogeneous helical body characteristic of the head of the adult spermatozoa. The nebenkern is apparently mitochondrial in nature and, in its early development, is similar to that of insects except that it appears as a double structure from the beginning. As differentiation proceeds, the mitochondria lose their membranes, and the residual, now denuded cristae, reorganize to give a parallel radial arrangement. In the last stages of development, the nebenkern derivations become applied to the sheath of the middle piece in a compact helical fashion. In the development of the atypical spermatozoa, the nucleus fails to differentiate and simply shrinks in volume until only a remnant, devoid of DNA, is left. The cytoplasm shows numerous vesicles containing small Feulgen-positive bodies, 80 to 130 mµ in diameter. These vesicles plus contents increase in number as spermatogenesis proceeds. The "head" structure of the atypical spermatozoa consists of a bundle (7 to 17) of tail flagella, each with a centriole at its anterior end. The end-piece of the atypical form appears brush-like and is made up of the free ends of the several flagella.  相似文献   

18.
The effect of x-irradiation on grasshopper spermatogenesis was studied with the aid of light and electron microscopy. The insects were irradiated at the second instar prior to the presence of maturation stages and observed at the last instar and imago stages. Dosages of 100 to 600 roentgens were found to retard the differentiation of the nucleus and mitochondrial nebenkern in spermatids. Evidence is presented that irradiation causes a curtailment and disorganization in the differentiation of the nebenkern from mitochondria. The above doses also induced the formation of supernumerary centrioles, flagellar filaments and acrosomes; nuclear disorganization as well as pycnosis and fragmentation also occur. The nucleus appears to be drawn toward each radiation-induced supernumerary acrosome, with consequent multipolarity of the nucleus. Induction of a set of flagellar filaments is seen only where the centriolar structure is in contact with the nucleus. Details are given of an organelle, heretofore not described, that is composed of anastomosed and interwoven cytoplasmic strands.  相似文献   

19.
长吻鮠精巢发育的分期及精子的发生和形成   总被引:9,自引:0,他引:9  
长吻鮠精巢的发育分为精原细胞增殖期、精母细胞生长期、精母细胞成熟期、精子细胞出现期,精子完全成熟期和精子退化吸收期。精巢的后1/3不产生也不贮存精子,精子的发生和形成经过精原细胞、精母细胞、精子细胞到精子的一系列过程。精原细胞有两种类型。精子无顶体,有中心粒帽,中片长,核凹窝和线粒体发达,鞭毛具侧鳍。  相似文献   

20.
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