毛蚶与青蚶精子超微结构及其所反映的蚶科进化关系

应用透射电镜技术,比较研究了毛蚶与青蚶精子的超微结构。毛蚶精子顶体为圆锥形,约为核长的1／2;精核无核前窝,具核后窝;中段横切面常见5个(偶见4个)线粒体环绕于中心粒周围;精子末段由轴丝及包绕轴丝的质膜组成,轴丝为典型的“9 2”结构。青蚶精子顶体轴向纵切面呈伞状,覆盖于细胞核前端,约为核长的1／3;精核具核前窝和核后窝;中段横切面常见有5个(偶见6个)线粒体环绕于中心粒周围;末段结构同毛蚶。顶体的形态、核前窝和核后窝的有无、中段线粒体的数量等是探索蚶科动物种间进化关系的线索。     

家鸽睾丸精子超微结构的观察

家鸽(Columbadomestica)精子分为头部、颈部及尾部。尾部又区分为中段、主段及末段。头部呈圆柱形,主要被精细胞核占据,核的前面包绕顶体,后端连接颈部。颈部有两个中心粒,与头部相邻接的是与精子纵轴垂直的近侧中心粒,远侧中心粒形成基底体向后发出尾部的轴丝。轴丝的结构为9+2型。中段在轴丝之外有线粒体鞘包绕,最外面为质膜。主段和末段无线粒体鞘,轴丝之外直接被以质膜。     

可口革囊星虫的精子发生及精子结构

为了探究可口革囊星虫(Phascolosoma esculenta)精子发生过程及结构上的特殊性,用显微及亚显微技术研究了可口革囊星虫的精子发生和精子结构。可口革囊星虫的精巢位于收吻肌基部,为一曲折的带状组织。成熟精巢内可观察到精原细胞、精母细胞以及精细胞等各阶段的生精细胞。在精子形成早期,很多精细胞脱离精巢,以精细胞团的形式掉落到体腔中。精细胞团内的精细胞同步发育为精子后,脱离精子团进入肾管。成熟精子由头部和尾部组成。头部由钟形顶体与鼓形细胞核构成。顶体后段下包于精核的前端。顶体分内、中、外三层,外层有横隔;顶体下腔内有颗粒状物质不均匀分布,中央有一束丝状纤维组成的顶体棒。核物质电子密度高,核内含空泡。无核前窝,具浅的核后窝。尾部分中段和末段,中段由6个(偶见5个或7个)线粒体围绕近、远端中心粒构成;末段细长鞭状,由轴丝及包绕轴丝的质膜组成,轴丝为典型的"9 2"结构。分析认为:可口革囊星虫精子发生过程以及超微结构上存在特殊的结构与机制:①精细胞团保证了精子形成的同步性;②顶体后段下包于精核的前端使精子头部小而灵巧,利于快速运动;③顶体的横隔使精子顶体的牢固性增强,确保受精时顶体反应的正常进行;④中段较多的线粒体使精子具有更强的环境适应性,有利于有效的受精。     

瘤背石磺的精子结构

用光学显微镜和透射电子显微镜技术研究了瘤背石磺精子的结构特点,分析了其生理生态适应性以及在肺螺亚纲系统演化中的意义。瘤背石磺的精子由头部、中段和末段组成。头部由奶嘴形的顶体和长圆筒状的细胞核构成。顶体包括顶体囊和顶体构架体两部分;两者的内含物都分布均匀,电子密度稍低于细胞核;顶体基部平整,与核前端之间有一空隙,内含物电子密度极低。细胞核由电子密度高的均匀颗粒物质组成,并出现核泡;核的后端有一"杯形"的凹陷,称为核后窝。中段结构复杂,主要包括一对位于核后窝内的中心粒、轴丝、质膜、线粒体及由线粒体衍生的糖原质螺旋体、基质层和类晶体层等。末段由"9 2"结构的轴丝及外包的质膜组成,无糖原质螺旋体和其它线粒体衍生物。比较瘤背石磺精子与肺螺亚纲其它物种的精子结构,我们认为该物种的精子属于"进化型",是一类在进化地位中比基眼目高等的动物。     

耳鲍精子的超微结构

本文利用透射电子显微镜对耳鲍(Haliotis asinina Linnaeus)精子的形态及超微结构进行了研究.研究结果表明:耳鲍的精子由头部、中段和尾部三部分组成,全长 41.6 μm.精子头部长 1.8 μm,头部由顶体、顶体下腔和细胞核组成,顶体电子密度比较均匀,呈圆锥形,长 0.6 μm,基部宽度为 0.65 μm,占头部长的 1/3;顶体下腔长 0.03 μm,宽为 0.65 μm,腔中含有中等电子密度物质;细胞核圆棒状,长 1.17 μm,核中部的宽度为 1.0 μm.精子中段较短,长 0.51 μm,宽 1.2 μm,主要由 5 个线粒体包围一对中心粒构成.尾部是一根鞭毛,从前到后逐渐变细,鞭毛是由细胞质膜包被的轴丝组成,轴丝为典型的"9 2"微管结构,即轴丝是由两个中心微管及均匀分布在中心微管周围的 9 对双联体微管组成.因此,耳鲍与其它鲍类精子的基本结构相似,形态结构的主要差异表现在三个方面:一是耳鲍精子的头部似圆锥形,长 1.8 μm,是目前已研究的鲍类中头部最短的种类;二是耳鲍精子顶体长比其基部宽要小,顶体电子密度比较均匀,顶体与核的电子密度差异不明显;三是耳鲍精子中段线粒体的数量为 5 个,没有发现 6 个线粒体现象的存在[动物学报 53(3):552-556,2007].     

虾夷扇贝精子的超微结构

用扫描和透射电镜研究了虾夷扇贝(Patinopecten yessoensis)精子的超微结构.虾夷扇贝精子为典型的原生型,全长50μm左右,头部长约3 μm.精子主要由头部、中段和尾部三部分组成.头部顶体突出,呈倒"V"形;顶体下方为精核,电子密度较高且占头部大部分,具有核前窝(anterior nuclear fossa)、核后窝(posterior nuclear fossa)和植入窝(implantation fossa);4～5个近圆形的线粒体围绕着中心粒复合体形成精子的中段.尾部细长,尾部鞭毛横切面为典型的"9 2"结构.     

拟目乌贼精子发生和精子的超微结构

应用扫描电镜和透射电镜观察了拟目乌贼(Sepia lycidas)精子的发生过程和超微结构。结果表明,精子发生经历了精原细胞、初级精母细胞、次级精母细胞、精细胞和成熟精子5个阶段,其中精细胞可以分为Ⅰ、Ⅱ、Ⅲ、Ⅳ、Ⅴ5个时期,精细胞Ⅱ期又可分为前期和后期。细胞核经历了一个横向收缩、纵向拉长的过程,由圆形或椭圆形,变为不规则的纺锤形、稍弯曲的长柱形;核内染色质由絮状,变为絮块状、致密颗粒状、细纤维状、粗纤维状和片层状,直至高电子密度均质状;顶体由圆形,变为头盔形、圆锥形、倒"U"字形,直至子弹头形;线粒体由空泡状经过融合和迁移,变为内嵴丰富的椭球形,形成不完全包围鞭毛的线粒体距。成熟精子全长101.28μm,由头部和尾部组成,头部呈长辣椒状,长7.73μm,宽1.51μm,由顶体和细胞核组成;尾部细长,为93.18μm,为典型的"9+2"结构,由中段、主段和末段三部分组成。     

大鲵精子结构研究

为了解大鲵精子超微结构,应用扫描电镜和透射电镜开展了大鲵精子形态结构研究。结果显示:大鲵精子由头部、颈部和尾部3部分组成。精子总长216.36μm±9.93μm(n=30),头部长65.80μm±3.70μm(n=30),颈部较短,多不明显,尾部长153.52μm±3.22μm(n=30)。头部由顶体、穿孔器和细胞核组成;颈部包括核窝、近端中心粒及远端中心粒、线粒体、轴丝和轴纤维;尾部无明显分段,由轴丝、轴纤维、轴丝旁纤维和波动膜组成。大鲵精子内线粒体较少,可能与精子运动缓慢、精子活力维持时间短有关;成熟过程中精子细胞头部包围的胞质分泌物中含有一定数量的线粒体。     

褶纹冠蚌精子的超微结构研究

利用电镜褶纹冠蚌精子的形态和结构作了研究,结果表明：精子全长约40-43μm,由头部、中段和鞭毛组成。头部呈子弹头形,长约2.6μm,直径约1.5μm,内含细胞核,核属浓缩型,外被核膜,5个球形的线粒体构成了精子的中段,中段长约0.6μm,最大直径约1.8μm。近端中心粒位于核基部的凹陷处,并通过致密的无定形的基质与远端中心粒相连,远端中心粒与鞭毛领之间通过硬功夫个围中心粒器紧密相连,鞭毛长约37-40μm。精子顶体退化,仅由几个顶体囊泡组成。     

拟目乌贼精子发生的超微结构

应用扫描电镜和透射电镜观察了拟目乌贼(Sepia lycidas)精子的发生过程和超微结构。结果表明,精子发生经历了精原细胞、初级精母细胞、次级精母细胞、精细胞和成熟精子五个阶段,其中精细胞可以分为Ⅰ、Ⅱ、Ⅲ、Ⅳ、Ⅴ五个时期,精细胞Ⅱ期又可分为前期和后期。细胞核经历了一个横向收缩、纵向拉长的过程,由圆形或椭圆形,变为不规则的纺锤形、稍弯曲的长柱形;核内染色质由絮状,变为絮块状、致密颗粒状、细纤维状、粗纤维状和片层状,直至高电子密度均质状;顶体由圆形,变为头盔形、圆锥形、倒“U”字形,直至子弹头形;线粒体由空泡状经过融合和迁移,变为内嵴丰富的鸡冠状,形成不完全包围鞭毛的线粒体距。成熟精子全长101.28μm,由头部和尾部组成,头部为稍弯曲的长柱形,长7.73μm,宽1.51μm,由顶体和细胞核组成;尾部细长,为93.18μm,为典型的“9 2”结构,由中段、主段和末段三部分组成。     

Ultrastructure of euspermatozoa and paraspermatozoa in the marine gastropod Adelomelon beckii (Caenogastropoda, Volutidae)

The sperm morphology of Adelomelon beckii is described by optical and transmission electron microscopy. Both euspermatozoa and paraspermatozoa were found in the specimens studied. Euspermatozoa are filiform and have an elongate nucleus capped by an acrosome. A small basal plate lies between the base of the acrosome and the nucleus. The mid-piece consists of U-shaped mitochondria wrapped helically around the central axoneme. A dense annulus at the junction of the mid-piece and glycogen piece is found, ending in a short end-piece, composed of the axoneme surrounded by a plasma membrane. Two types of paraspermatozoa are found, both vermiform but differing internally with respect to the disposition and number of axonemes, as well as to the types of secretory vesicles. We suggest the use of paraspermatozoa as a systematic character to reveal phylogenetic relationships in this family.     

Spermatozoon structure and spermiogenesis in Nassarius kraussianus (Gastropoda,Prosobranchia, Nassariinae)

Summary

The testis of Nassarius kraussianus (Nassariinae) produces two types of spermatozoa, a motile euspermatozoon and a non-motile paraspermatozoon. The euspermatozoon is filiform and about 95/μm long. The elongated head (40 μm long) is comprised of a slender nucleus (about 0.5 μm diameter) which is penetrated throughout by an intranuclear canal housing the anterior portion of the axoneme. A short (about 2 μm long) conical acrosome surmounts the nucleus anteriorly. The mid-piece (23 μm in length) consists of six to seven modified mitochondria which are helically arranged around the axoneme. Posterior to the mid-piece the tail is composed of a short glycogen piece and an end piece. The paraspermatozoon is spindle-shaped (about 50 μm long) and contains multiple (16–20) axonemes the basal bodies of which fuse anteriorly. Posteriorly, numerous small mitochondria and electron-dense bodies lie between the axonemes. Structural changes during eu- and paraspermiogenesis mirror those described for other species of gastropod mollusc with dimorphic spermatozoa. However unlike other molluscs, the cytoplasmic bridges which connect developing spermatids contain well developed stacks of endoplasmic reticulum which form a continuum with that in the cytoplasm of the spermatids. These structures may in some way facilitate the synchronous development of the spermatozoa.     

Morphology and fine structure of Acipenser persicus (Acipenseridae, Chondrostei) spermatozoon: Inter-species comparison in Acipenseriformes

This study describes morphology and fine structure of the Persian sturgeon (Acipenser persicus) (Acipenseridae, Chondrostei) spermatozoon. The results show that the spermatozoon of A. persicus is differentiated into an elongated head (length: mean±SD: 7.1±0.5μm) with an acrosome (length: 1.2±0.2μm), a cylindrical midpiece (length: 1.8±0.5μm), a flagellum (length: 50.3±5.9μm) and a total length of 59.2±6.2μm. Ten posterolateral projections (PLPs) arise from the posterior edge of the acrosome and there were 3 endonuclear canals that traversed the nucleus from the acrosomal end to the basal nuclear fossa region. Three to six mitochondria were in peripheral midpiece and the proximal and distal centrioles were located near to "implantation fossa" and basement of the flagellum. The axoneme has a typical eukaryotic structure composed of 9 peripheral microtubules and a central pair of single microtubule surrounded by the plasma membrane. Lateral fins were observed along the flagellum. The fins started and ended at 0.5-1μm from midpiece and at 4-6μm from the end of flagellum. There were significant differences in the size of almost all measured morphological parameters between males and flagellar, midpiece and nucleus characters were more isolated parameters that can be considered for detecting inter-individual variations. This study showed that sperm morphology and fine structure are similar among sturgeon species, but the dimensions of the parameters may differ.     

Ultrastructure of Sperm in <Emphasis Type="Italic">Mercenaria stimpsoni</Emphasis> and <Emphasis Type="Italic">Mactra chinensis</Emphasis> (Mollusca: Bivalvia) from the Sea of Japan

The ultrastructure of the sperm of the common bivalve species Mercenaria stimpsoni and Mactra chinensis from Peter the Great Bay is described. The sperm structure is typical for animals with external insemination. The sperm consists of a head, middle part, and flagellum. The sperm head of M. stimpsoni has a curved crescent form and includes the nucleus and acrosome; the head length is 9.8 μm. The acrosome is subdivided to the acrosome granule and the periacrosomal material. There are 4 mitochondria of about 0.8 μm in size in the middle part of the spermatozoon. The mitochondria surround the centriolar apparatus, which consists of proximal and distal centrioles located at a right angle. The axoneme originates from the distal centriole. The sperm of M. chinensis is barrel-shaped, with a head length of 3.2 μm. The acrosome is relatively larger, and its height is 1–1.2 μm. There are also 4 mitochondria 0.6–0.8 μm in the middle part of the spermatozoon. The sperm structure of the described species is typical of the families to which the mollusks belong, with insignificant variations.     

The length of a short sperm: Elongation and shortening during spermiogenesis in Cotesia congregata (Hymenoptera,Braconidae)

The spermatozoon of the parasitoid wasp Cotesia congregata is an extremely short gamete measuring less than 7 μm; it is as yet the shortest flagellated sperm to be identified. The mature sperm consists of an acrosome, surrounded by an extra cellular coat, a condensed nucleus, two uncoiled mitochondrial derivatives and a short axoneme. Testes of young adults contain a continuum of differentiation stages. Initially, the flagellum is approximately 5 μm long. It conserves its length in round, elongated and mature spermatids, but is reduced to less than 3 μm in mature spermatozoa. The nucleus is 2 μm in diameter when round, 10 μm long when it becomes a long boat-hull shaped filament, and then reduces to 3.6 μm. Thus, during development the gamete reaches a total length of 15 μm before finally reducing to less than half that length. Some traits of mature sperm anatomy are similar to related species of the Braconidae family, but others seem to be specific and could be due to the shortness of the cell. This uncommon elongation and subsequent shortening of such a tiny flagellated cell constitutes a model for both nucleus and cilium development.     

中国绿螂精子的超微结构

应用透射电镜技术观察了中国绿螂(Glaucomya chinensis)精子的超微结构。精子为典型的原生型,包括头部、中段和尾部三部分。头部由顶体和细胞核组成。顶体呈倒"V"字型。细胞核呈长圆柱形,没有核前窝,具有核后窝。中段由4个线粒体环绕中心粒而成。尾部细长,为典型的"9+2"结构。文中还讨论了双壳类精子形态结构的种属间差异。     

An ultrastructural analysis of the mature spermatozoon of Anguispira alternata (say) (pulmonata,stylommatophora)

Mature spermatozoa from the hermaphroditic duct of adult snails were examined using various techniques of light microscopy as well as scanning and transmission electron microscopy. The sperm are approximately 557 μm in length including a dextrally spiral head approximately 13 μm long. The head consists of an electron-dense nucleus sculptured into a double-ridged spiral and an acrosome projecting approximately 0.45 μm beyond the apex of the nucleus. The acrosome consists of a membrane-bound vesicle approximately 0.1 μm in diameter and a column of homogeneous material which extends along one side of the terminal spiral of the nucleus. This material is separated from the nucleus by the nuclear envelope. The neck region, though similar to that found in other pulmonates, possesses a unique coiled structure surrounding the central doublet of the axoneme. The midpiece axoneme possesses a 9+9+2 configuration anteriorly grading into a 9+2 pattern for the majority of its length. There are three mitochondrial helices – one primary and two secondary – in the midpiece. Only the primary helix persists throughout the midpiece.