三疣梭子蟹精子顶体反应过程中的形态和结构变化

用离子载体A2 3187和卵水人工诱导三疣梭子蟹精子的顶体反应 ,分别获得 75 33%和 84 83%的顶体反应率。应用光镜和电镜技术观察了顶体反应前后精子形态和结构的变化。未处理精子呈陀螺形 ,由顶体、核杯和 5 - 10条核辐射臂组成。顶体包括顶体囊和顶体管。顶体囊的伞形头帽拥有约 70条辐射肋。连续发生的精子顶体反应过程被人为地分为四个阶段 :(1)头帽鼓起 ;(2 )顶体囊外翻 ;(3)穿孔器前伸 ,顶体囊膜翻转 ;(4 )顶体囊膜脱落 ,顶体丝形成。直到第四阶段才观察到钉状精子的辐射臂开始收缩。探讨了辐射臂和穿孔器前冲在精子入卵中的功能     

长江华溪蟹精子超微结构的研究

透射电镜下观察长江华溪蟹成熟精子的形态和超微结构。精子呈椭球形,无鞭毛,具数条由核延伸而成的辐射臂精子。由球形的顶体,膜复合体,核杯及辐射臂组成,顶体由头帽,亚帽带,丁体囊及中央管组成。在中央管的基部发现有中心粒。核膜与质膜紧贴在一起形成了精子的界膜。     

锯缘青蟹精子超微结构的研究

利用光镜和电镜观察了锯缘青蟹成熟精子的形态和超微结构。精子呈陀螺形，无鞭毛，在较宽的一端环生着１０余辐射臂。精子由球状的顶体、核杯以及核衍生的辐射臂三部分组成。顶体包括顶体管和顶体囊，后者包绕在顶体管的中央管周围，并可分为头帽带，内层和外层区。顶体被杯状的核包裹，仅头帽露于精子表面。成熟的精子中，位于核杯和顶体管之间的核膜出现局部断续或消失，中心粒和一些胞器出现的核杯腔中。     

受精过程中的顶体反应

各类动物精子的顶体结构大体相似,它位于核的前端,为一顶体膜包围的囊状结构,这就是顶体囊。在它和核之间有一顶体下腔,内有未聚合的肌动蛋白。当精子遇到卵膜时,顶体膜和其外的质膜发生融合,释放内含的顶体酶;与此同时,顶体下腔内的肌动蛋白发生聚合形成顶体突起。由此突起附着于卵膜,藉精子的运动和顶体酶的作用,使精子穿过孵膜而     

北草蜥精子的超微结构--兼评不同类群蜥蜴精子形态的差异

应用透射电镜对北草蜥精子的超微结构研究结果表明,北草蜥精子头部顶体囊始终呈圆形,由皮质和髓质组成;顶体囊单侧脊的皮质与髓质问具电子透亮区;穿孔器1个,无穿孔器基板;具顶体下腔;细胞核长形,核内小管缺,核前电子透亮区缺,核肩圆。尾部颈段具片层结构。中段短,多层膜结构缺;纵切面上具2层线粒体;横切面上每圈线粒体6个;2组致密体,具连续的环状结构;线粒体与环状结构的排列模式：rs1／mi1、rs2／mi2;纤维鞘伸人中段,具终环。主段前面部分具薄的细胞质颗粒区;纤维3和8至主段前端消失;轴丝呈“9＋2”型。蜥蜴科内不同种类的线粒体数目不同,但都具有2组致密体。不同类群蜥蜴的顶体囊、顶体下腔、核前电子透亮区、穿孔器基板、核肩,以及线粒体与致密体的数目和排列方式等精子超微结构特征都为研究蜥蜴的系统发生提供了辅助信息。     

三疣梭子蟹精卵相互作用的扫描电镜观察

应用扫描电镜技术观察了三疣梭子蟹的精卵相互作用。未受精成熟卵表面较光滑、无受精孔,但有许多微孔。成熟卵外被卵膜,内为卵母细胞。在卵自然产出后,精子迅速发生顶体反应使顶体囊外翻并压入卵膜,而核仍留于卵膜外,核辐射臂不收缩且仍附着于卵膜上。三疣梭子蟹为多精着卵和多精入卵膜。精子外翻顶体囊压入卵膜后,核辐射臂陆续回缩直至消失。作用于顶体丝上的卵母细胞主动拖精作用对入卵膜精子的进一步入卵、受精至关重要,环状卵膜突起的向心伸展也有一定的协助作用。探讨了着卵精子的顶体反应、精子入卵膜的机制及卵子在精子入卵过程中的作用     

东方扁虾精子发生的超微结构

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。     

中国鲎精子发生的研究: Ⅰ.精子的发生过程

利用光镜和电镜技术,结合细胞化学方法研究了中国鲎（Ｔａｃｈｙｐｌｅｕｓ ｔｒｉｄｅｎｔａｔｕｓ）精子发生过程．结果表明：中国鲎精子发生可划分为精原细胞、初级精母细胞、次级精母细胞、精子细胞及精子五个时期。在精子发生中,出现顶体丝结构,这是鲎精子发生的一个重要特征。页体由顶囊和亚顶体间隙组成。顶体丝由顶体囊底部发出,穿过亚顶体间隙,贯穿核中央部分的通道．沿核底部穿出,绕核缠绕,形成约２８匝的百体丝螺圈。这一特点可能与精子在受精时必须穿越厚的卵膜密切相关。成熟精子头部如梨形,前端覆盖有吸盘状后帽,头部长约４μｍ,尾部鞭毛长达３５μｍ、鞭毛为９ ×２结构,在鞭毛基部有一对中心粒。     

受精过程中的顶体反应

各类动物精子的顶体结构大体相似,位于核的前端,为一顶体膜包围的囊状结构,这就是顶体囊.在它和核之间有一顶体下腔,内有未聚合的肌动蛋白.当精子遇到卵膜时,顶体膜和其外的质膜发生融合,释放内含的顶体酶.与此同时,顶体下腔内的肌动蛋白发生聚合,形成顶体突起.由此突起附着于卵膜,借精子的运动和顶体酶的作用,使精子穿过卵膜而与卵的质腹相遇融合而受精.     

三疣梭子蟹精子顶体反应前后胞内Ca~(2+)的变化

应用激光扫描共聚焦显微镜(LSCM)和Fluo-3/AM荧染技术对三疣梭子蟹精子顶体反应前后的胞内Ca2 变化进行了观察和检测.结果显示,在精子顶体反应过程中,胞内Ca2 主要分布在细胞核、穿孔器和胞质膜残存处,胞内Ca2 浓度([Ca2 ]I)总体上呈现先上升后下降的趋势.顶体反应前精子的平均荧光强度为35.95±5.71;穿孔器前伸、顶体囊膜翻转阶段精子的平均荧光强度为66.80±7.35;顶体囊膜脱落、顶体丝形成阶段精子的平均荧光强度为3.87±2.82;上述各阶段间精子荧光强度有极显著差异(P<0.01).顶体反应穿孔器前伸、顶体囊膜翻转阶段的精子相比顶体反应前精子,[Ca2 ]I显著提高;而在顶体囊膜脱落、顶体丝形成阶段,[Ca2 ]I则急剧下降,只在顶体丝基部胞质膜残存处有微量Ca2 存在.初步探讨了三疣梭子蟹精子顶体反应前后胞内Ca2 变化的功能.     

An ultrastructural analysis of mature sperm from the crayfish Pacifastacus leniusculus,Dana

Sperm from the crayfish, Pacifastacus leniusculus, resemble other reptantian sperm in that they are composed of an acrosome, subacrosomal region, nucleus, membrane lamellar complex, and spikes which radiate from the nuclear compartment. The acrosome (PAS positive vesicle) can be subdivided into three regions: the apical cap, crystalline inner acrosomal material, and outer acrosomal material which is homogeneous except for a peripheral electron dense band. The nucleus contains uncondensed chromatin and bundles of microtubules which project into the spikes. The orientation of the microtubule bundles relative to the nuclear envelope near the base of the subacrosomal region suggests that the nuclear envelope may function in the organization of the spike microtubules.     

Fine structure of the spermatozoon of Marthasterias glacialis (Linnaeus) (Echinodermata; Asteroidea), with special reference to acrosomal morphology

The sperm of Marthasterias glacialis (Linnaeus) was studied by light and electron microscopy. It is a long uniflagellated cell of the “primitive” type. The head has a spherical shape and contains a nucleus with a spheroid acrosome lying in a cup-shaped anterior fossa. The acrosome is formed by an acrosomal vesicle surrounded by the periacrosomal material. The basal specializations of the acrosomal vesicle show a clear differentiation of its constituents resembling the structure of membrane. The midpiece contains a very large annular mitochondrion which encircles two perpendicular centrioles. The distal centriole is in close association with a pericentriolar radial complex. The tail, containing a common microtubular axoneme, is projected to a variable position.     

The fine structure of the sperm of a holothurian and an ophiuroid

The fine structure of the mature sperm of the holothurian, Cucumaria miniata, and the ophiuroid, Ophiopholis aculeata, is described with particular reference to their acrosomal and centriolar satellite complexes, and compared to the sperm of other echinoderms. In Cucumaria, the acrosome is in the form of a diffuse acrosomal vesicle. It is unusual in that it apparently lacks an acrosomal membrane. A membrane separating the acrosomal vesicle from the periacrosomal material may not be equivalent to a typical inner acrosomal membrane. In Ophiopholis, the acrosome is dense, with some internal substructure, and is enclosed by a complete acrosomal membrane. In both species, the acrosome is partially surrounded by an amorphous periacrosomal mass. There is a notable absence of a subacrosomal depression and associated structures as found in other echinoderm sperm. The centriolar satellite complex (CSC) is essentially identical in both species. A reconstruction of the CSC is presented. The CSC consists of nine satellites radiating angularly from the distal centriole, each bifurcating at a dense node before inserting on a marginal ring containing circumferential microtubules. The ring is probably a cytoskeletal element. Immediately below the satellites are nine Y-shaped connectives. connecting each of the axonemal alpha doublets to the flagellar membrane.     

The ultrastructural organization of the mature spermatozoon of Luidia clathrata (Say) (Echinodermata: Asteroidea)

The sperm of Luidia clathrata are morphologically typical of asteroid sperm. The head is spherical and contains the nucleus and acrosomal complex. The nucleus has an anterior indentation in which rests the acrosomal complex. There is no evidence of a centriolar fossa along the posterior border of the nucleus. The acrosome is a cup-shaped structure containing a less electron dense central region. The periacrosomal material is homogeneous in nature, and the subacrosomal specialization of the periacrosomal materials appear as bands of varying electron density. The middle piece is an annular band of mitochondria which surrounds the proximal and distal centrioles. The centrioles exhibit the typical nine triplet arrangement. Both the centrioles and the axoneme project to one side of the middle piece region. Associated with the distal centriole is an elaborate pericentriolar process.     

Sperm ultrastructure of the spider crab Maja brachydactyla (Decapoda: Brachyura)

This study describes the morphology of the sperm cell of Maja brachydactyla, with emphasis on localizing actin and tubulin. The spermatozoon of M. brachydactyla is similar in appearance and organization to other brachyuran spermatozoa. The spermatozoon is a globular cell composed of a central acrosome, which is surrounded by a thin layer of cytoplasm and a cup‐shaped nucleus with four radiating lateral arms. The acrosome is a subspheroidal vesicle composed of three concentric zones surrounded by a capsule. The acrosome is apically covered by an operculum. The perforatorium penetrates the center of the acrosome and has granular material partially composed of actin. The cytoplasm contains one centriole in the subacrosomal region. A cytoplasmic ring encircles the acrosome in the subapical region of the cell and contains the structures‐organelles complex (SO‐complex), which is composed of a membrane system, mitochondria with few cristae, and microtubules. In the nucleus, slightly condensed chromatin extends along the lateral arms, in which no microtubules have been observed. Chromatin fibers aggregate in certain areas and are often associated with the SO‐complex. During the acrosomal reaction, the acrosome could provide support for the penetration of the sperm nucleus, the SO‐complex could serve as an anchor point for chromatin, and the lateral arms could play an important role triggering the acrosomal reaction, while slightly decondensed chromatin may be necessary for the deformation of the nucleus. J. Morphol., 2010. © 2009 Wiley‐Liss, Inc.     

乌梢蛇精子头部形成的超微结构

摘要：为了解乌梢蛇（Zaocys dhumnades）精子形成的规律,用透射电镜对其头部超微结构进行了观察。结果表明,乌梢蛇精子头部形成可分为4个阶段：阶段Ⅰ,前顶体囊泡内的颗粒物质融合形成1个顶体颗粒而发育为顶体囊泡,随着顶体囊泡的增大,在顶体囊泡与核膜之间形成了致密的纤维物质层。阶段Ⅱ,顶体囊泡变扁平,顶体颗粒分散...     

Fine structure of an elongated dorso-ventrally compressed echinoderm (holothuroidea) spermatozoon

The spermatozoon of Cucumaria pseudocurata is unique among those of the echinoderms in that it is tabloid in shape, i.e., elongated and dorsoventrally compressed. The sperm consists of a dorsal surface which contains an extensive striated rootlet-like structure located within a dorsal groove and a ventral surface which contains a medially situated acrosome. A single mitochondrion lies at the base of the nucleus. The flagellum is unusual in that a 9 + 3 tubular arrangement is observed in the mid-tail region. The acrosome consists of an acrosomal granule bounded by a limiting membrane and a surrounding periacrosomal layer. The granule is irregular in shape with the anterior-posterior surfaces flaring out, forming pockets in the periacrosomal material. The ventral granule surface bulges forming a close association with the plasma membrane. The dorsal surface is indented. Ventral to the depression (within the granule) is a small area containing a particulate-fibrous material. To the inside of the granule limiting membrane there is a second membrane-like structure (incomplete) which extends from the anterior-posterior surfaces around the dorsal face of the granule. Dorso-medial to the granule the periacrosomal layer contains a particulate-fibrous region lodged within the granule depression. This material is presumably the precursor of the acrosomal filament. Prominent cytoplasmic folds extend off from the basal flagellar region. The proximal and distal centrioles are situated perpendicular to one another within the mitochondrion. Centriolar satellite materials are associated with both centrioles. Toward the base of the tail the satellite of the distal centriole consists of nine radiating arms extending at an angle of 45° to the axis of the centriole. Each arm terminates in a dense thickening. The striated rootlet extends anteriorly from the distal centriole to just below the level of the acrosome.     

Ultrastructure of spermatogenesis in the sea star,Asterina minor

The ultrastructural features of spermatogenesis were investigated in the hermaphroditic sea star Asterina minor. The primordial germ cells in the genital rachis contain small clusters of electron-dense material (nuage material) and a stack of annulate lamellae. They also have a flagellum and basal body complex situated close to the Golgi complex. After the development of the genital rachis into the ovotestis, spermatogenic cells increase in number and differentiation begins. Nuage material is observed in spermatogonia, but it gradually disappears in spermatocytes. The annulate lamellae do not exist beyond the early spermatogonial stage. By contrast, a flagellum and basal body complex are found throughout spermatogenesis. The Golgi-derived proacrosomal vesicles appear in the spermatocyte and coalesce to form an acrosomal vesicle in the early spermatid. The process of acrosome formation is as follows: (1) a lamella of endoplasmic reticulum (ER) continuous with the outer nuclear membrane encloses the posterior portion of the acrosomal vesicle; (2) the vesicle attaches to the cell membrane with its anterior portion; (3) periacrosomal material accumulates in the space between the acrosomal vesicle and the ER; (4) the nucleus proper changes its features to surround the acrosome; (5) amorphous, electron-dense material is deposited under the electron-dense disk; and (6) the nucleus forms a hollow opposite the electron-dense material.     

Spermiogenesis and sperm structure in the crabUca tangeri (Crustacea,Brachyura), with special reference to the acrosome differentiation

Summary Early spermatids of the crabUca tangeri consists of the nucleus of granular chromatin and the cytoplasm, which contains a proacrosomal vesicle in close association with membrane lamellae. In the mid spermatids an invagination of the acrosomal vesicle membrane gives rise to the formation of the perforatorium, a spindle-shaped tubule which encloses tubular membranous structures. The pair of centrioles located at the base of the acrosome is not directly involved in perforatorial differentiation. The acrosomal vesicle shows a heterogeneous content composed of the operculum, the thickened ring, and three layers of different materials concentrically arranged around the perforatorium. During the late spermatid stage the nuclear profile differentiates numerous slender arms and the chromatin arranges into fibers. Membranous tubules from the cytoplasm become incorporated into the tubular structures of the perforatorium. The mature spermatozoon has the typical structure of the branchyuran sperm, with a complex acrosome, cupped by the nucleus, and a thin cytoplasmic band intervening between the former main elements. The centrioles are degenerate. The nuclear arms are unusually numerous (more than 20) and lack microtubules or microtubular derivatives.     

ROLE OF THE GAMETE MEMBRANES IN FERTILIZATION IN SACCOGLOSSUS KOWALEVSKII (ENTEROPNEUSTA) : I. The Acrosomal Region and Its Changes in Early Stages of Fertilization

Previous electron microscope studies of sperm-egg association in the annelid Hydroides revealed novel aspects with respect to the acrosomal region. To determine whether these aspects were unique, a comparable study was made of a species belonging to a widely separated phylum, Hemichordata. Osmium tetroxide-fixed polyspermic material of the enteropneust, Saccoglossus, was used. The acrosomal region includes the membrane-bounded acrosome, with its large acrosomal granule and shallow adnuclear invagination, and the periacrosomal material which surrounds the acrosome except at the apex; here, the acrosomal membrane lies very close to the enclosing sperm plasma membrane. After reaching the egg envelope, the spermatozoon is activated and undergoes a series of changes: the apex dehisces and around the resulting orifice the acrosomal and sperm plasma membranes form a continuous mosaic membrane. The acrosomal granule disappears. Within 7 seconds the invagination becomes the acrosomal tubule, spans the egg envelopes, and meets the egg plasma membrane. The rest of the acrosomal vesicle everts. The periacrosomal mass changes profoundly: part becomes a fibrous core (possibly equivalent to a perforatorium); part remains as a peripheral ring. The basic pattern of structure and sperm-egg association in Saccoglossus is the same as in Hydroides. Previous evidence from four other phyla as interpreted here also indicates conformity to this pattern. The major role of the acrosome is apparently to deliver the sperm plasma membrane to the egg plasma membrane.