东方扁虾精子的超微结构

利用电镜研究了东方扁虾（Ｔｈｅｎｕｓ ｏｒｉｅｎｔａｌｉｓ）精子的形态和结构。精子由核、膜复合物区和顶体区３部分组成。核内含非浓缩的染色质、微管及细纤维丝,外被核膜;５～６条辐射臂自核部位伸出,臂内充满微管。膜复合物区位于核与顶体之间,由许多膜片层结构及其衍生的囊泡共同组成。顶体区由顶体囊和围顶体物质组成,顶体结构复杂,由顶体帽、内顶体物质和外顶体物质等构成;围顶体物质呈细颗粒状,主要分布于顶体囊     

Assembly of the fluorescent acrosomal matrix and its fate in fertilization in the water strider,Aquarius remigis

Animal sperm show remarkable diversity in both morphology and molecular composition. Here we provide the first report of intense intrinsic fluorescence in an animal sperm. The sperm from a semi‐aquatic insect, the water strider, Aquarius remigis, contains an intrinsically fluorescent molecule with properties consistent with those of flavin adenine dinucleotide (FAD), which appears first in the acrosomal vesicle of round spermatids and persists in the acrosome throughout spermiogenesis. Fluorescence recovery after photobleaching reveals that the fluorescent molecule exhibits unrestricted mobility in the acrosomal vesicle of round spermatids but is completely immobile in the acrosome of mature sperm. Fluorescence polarization microscopy shows a net alignment of the fluorescent molecules in the acrosome of the mature sperm but not in the acrosomal vesicle of round spermatids. These results suggest that acrosomal molecules are rearranged in the elongating acrosome and FAD is incorporated into the acrosomal matrix during its formation. Further, we followed the fate of the acrosomal matrix in fertilization utilizing the intrinsic fluorescence. The fluorescent acrosomal matrix was observed inside the fertilized egg and remained structurally intact even after gastrulation started. This observation suggests that FAD is not released from the acrosomal matrix during the fertilization process or early development and supports an idea that FAD is involved in the formation of the acrosomal matrix. The intrinsic fluorescence of the A. remigis acrosome will be a useful marker for following spermatogenesis and fertilization. J. Cell. Physiol. 226: 999–1006, 2011. © 2010 Wiley‐Liss, Inc.     

Proacrosome and acrosome of the spermatozoon in Acanthobdella peledina (Annelida: Clitellata)

Summary

Proacrosome and acrosome of the primitive leech Acanthobdella peledina are described by means of transmission electron microscopy. The proacrosome develops in early spermatids and has the shape of a pot-bellied urn with an opening towards the nucleus. Its wall is formed by a thin vesicle. In its interior, many sections of tubular structures are visible. This urn is seated atop a short, electron-dense tube. The resultant acrosome is unusually elongated, with a helically coiled acrosomal tube forming its base. Above the tube the thin acrosomal vesicle encloses a central space, within which is the acrosomal rod. The acrosomal structures clearly indicate a sister-group relationship to the Euhirudinea, but do not corroborate the notion of close kinship with the Branchiobdellidae.     

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.     

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.     

Ultrastructure of the Tubificid Acrosome (Annelida, Oligochaeta)

The later morphogenesis of the acrosome of Limnodriloides winckelmanni and Rhyacodrilus arthingtonae is compared with that in Enchytraeus and in earthworms. After superposition of the acrosome on the tip of the nucleus the manchette continues apically beyond the nucleus to ensheath the acrosomal tube. At the posterior limit of, and probably contained in, the spacious/ terminal primary acrosomal vesicle is an electron-dense ring. A domed protrusion into the floor of the primary vesicle is tentatively regarded as the secondary acrosome vesicle. The axial rod when first observed is attached to the vesicle complex. Later, the rod detaches and extends deeply into the acrosome tube. A membrane ensheathes the tubificid axial rod but its exact homology with the complex layers surrounding the lumbricid or megascolecid axial rod is not clear. The domed apical region of the tubificid acrosome is probably a persistence of the primary acrosome vesicle and it is deduced that the acrosome vesicle surrounding the axial rod in lumbricids and megascolecids is a product, by invagination, of the secondary acrosome vesicle only.     

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.     

Differentiation of the acrosomal complex in ostrich (Struthio camelus) spermatids

The acrosomal complex of ostrich sperm consists of a small, cone-shaped acrosome and a slender, cylindrical perforatorium housed within a deep endonuclear canal. The perforatorium is almost exclusively endonuclear in location and is only covered by the acrosome at its point of origin in the apical subacrosomal space. The development of the acrosome is generally similar to that described in other non-passerine birds. Small proacrosomal granules (vesicles) emanating from the Golgi apparatus coalesce to form a large, membrane-bound acrosomal vesicle filled with homogeneous, electron-dense material. The acrosomal vesicle attaches to the nucleus via a shallow depression and subsequently collapses to form the typical cap-like acrosome of non-passerine birds. In ostrich spermatids the endonuclear canal becomes obvious when the collapsed acrosomal vesicle has assumed a dumbbell-shaped appearance. The perforatorium, which originates from moderately electron-dense material contained within the apical subacrosomal space, expands within the deepening endonuclear canal. The material of the perforatorium does not originate in the form of an obvious granule as in chicken and budgerigar spermatids. Indications are that in ostrich spermatids the developing acrosome plays a role in the shaping of the tip of the nucleus. The perforatorium, however, appears to represent a residual structure that has no specifically identified function. © 1996 Wiley-Liss, Inc.     

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.     

Ultrastructure of spermiogenesis of Philippia (Psilaxis) oxytropis,with special reference to the taxonomic position of the architectonicidae (Gastropoda)

Summary Spermiogenesis of the architectonicid Philippia (Psilaxis) oxytropis was studied using transmission electron microscopy. Both spermatids and mature sperm of Philippia show features comparable to sperm/spermatids of euthyneuran gastropods (opisthobranchs, pulmonates) and not mesogastropods (with which the Architectonicidae are commonly grouped). These features include: (1) Accumulation of dense material on the outer membrane of anterior of the early spermatid nucleus — this material probably incorporated into the acrosome; (2) Structure of the unattached and attached spermatid acrosome (apical vesicle, acrosomal pedestal) accompanied by curved (transient) support structures; (3) Formation of the midpiece by individual mitochondrial wrapping around the axonemal complex, and the subsequent fusion and metamorphosis of the mitochondria to form the midpiece; (4) Presence of periodically banded coarse fibres surrounding the axonemal doublets and intra-axonemal rows of granules. A glycogen piece occurs posterior to the midpiece but is a feature observed in both euspermatozoa of mesogastropods (and neogastropods) and in sperm of some euthyneurans.Despite the lack of paracrystalline material or glycogen helices within the midpiece (both usually associated with sperm of euthyneurans), the features of spermiogenesis and sperm listed indicate that the Architectonicidae may be more appropriately referable to the Euthyneura than the Prosobranchia.Abbreviations a acrosome - ap anterior region of acrosomal pedestal - as support structures of spermatid acrosome - av apical vesicle of acrosome (acrosomal vesicle of un-attached acrosome) - ax axoneme - b basal region of acrosomal pedestal - c centriole - cf coarse fibres - cr cristal derivative of midpiece - db intra-axonemal dense granules - drs dense ring structure - gg glycogen granules - gp glycogen piece - G Golgi complex - m mitochondrion - mt microtubules - n nucleus - pm plasma membrane - sGv small Golgi vesicles     

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。     

Ultrastructure of spermiogenesis in the American alligator,Alligator mississippiensis (Reptilia,Crocodylia, Alligatoridae)

Testicular samples were collected to describe the ultrastructure of spermiogenisis in Alligator mississipiensis (American Alligator). Spermiogenesis commences with an acrosome vesicle forming from Golgi transport vesicles. An acrosome granule forms during vesicle contact with the nucleus, and remains posterior until mid to late elongation when it diffuses uniformly throughout the acrosomal lumen. The nucleus has uniform diffuse chromatin with small indices of heterochromatin, and the condensation of DNA is granular. The subacrosome space develops early, enlarges during elongation, and accumulates a thick layer of dark staining granules. Once the acrosome has completed its development, the nucleus of the early elongating spermatid becomes associated with the cell membrane flattening the acrosome vesicle on the apical surface of the nucleus, which aids in the migration of the acrosomal shoulders laterally. One endonuclear canal is present where the perforatorium resides. A prominent longitudinal manchette is associated with the nuclei of late elongating spermatids, and less numerous circular microtubules are observed close to the acrosome complex. The microtubule doublets of the midpiece axoneme are surrounded by a layer of dense staining granular material. The mitochondria of the midpiece abut the proximal centriole resulting in a very short neck region, and possess tubular cristae internally and concentric layers of cristae superficially. A fibrous sheath surrounds only the axoneme of the principal piece. Characters not previously described during spermiogenesis in any other amniote are observed and include (1) an endoplasmic reticulum cap during early acrosome development, (2) a concentric ring of endoplasmic reticulum around the nucleus of early to middle elongating spermatids, (3) a band of endoplasmic reticulum around the acrosome complex of late developing elongate spermatids, and (4) midpiece mitochondria that have both tubular and concentric layers of cristae. J. Morphol., 2010. © 2010 Wiley‐Liss, Inc.     

Video microscopic analysis of ionophore induced acrosome reactions of lobster (Homarus americanus) sperm

Sperm from the American lobster (Homarus americanus) are normally nonmotile. However, during fertilization, the sperm undergo a calcium-dependent acrosome reaction that propels them forward about 18 μMm. The reaction occurs in two phases, eversion and ejection, which take place too quickly to permit analysis by direct observation. The purposes of this study were to examine the structural changes occurring in sperm during the normal acrosome reaction and to determine the rate of the reaction using video microscopy. The reaction was induced in vitro by ionophore A23187 and recorded using a video system attached to a Nikon Nomarski interference microscope. Videotapes were played back frame by frame (30 frames/sec), and images of reactions from 10 sperm were analyzed. The acrosome reaction, including the eversion of the acrosomal vesicle and ejection of the subacrosomal material and nucleus, can be divided into 4 steps: (1) expansion of the apical cap followed by expansion of the remainder of the acrosomal cylinder; expansion of the cylinder begins at its apical end and proceeds toward its base, (2) eversion of the apical half of the acrosomal vesicle and initial contraction of the apical cap, (3) eversion of the basal half of the acrosomal vesicle, continued contraction of the apical cap, and ejection of the subacrosomal material and nucleus, and (4) final contraction of the apical cap and ejection of the acrosomal filament. During steps 2, 3, and 4, the mean forward movement of sperm is 12.7, 3.9, and 1.1 μMm, respectively. Although the time required to complete the reaction ranged from 0.66 to 5.16 s, most sperm reacted in less than 3. s, and these sperm were considered to have typical rates. For sperm that reacted in less than 3 s, both step 1 and step 4 take about 0.2 s and show little variation among sperm. the time required to complete steps 2 and 3 averaged 0.63 and 0.37 s, respectively. Forward movement of the sperm during the acrosome reaction is caused by eversion of the inner and outer acrosomal material and contraction of the apical cap. The protein(s) responsible for this contraction is not yet known. © 1993 Wiley-Liss, Inc.     

Multiple acrosomal vesicles and their differentiation during spermiogenesis in Ascidia zara and Ascidia gemmata (Ascidiacea, tunicata).

A fully differentiated spermatozoon of both Ascidia zara and Ascidia gemmata is approximately 35 microM long. It contains a head and a tail lacking a midpiece. The head (approximately 4 microM long for A. zara and 5 microM long for A. gemmata) contains an elongated nucleus and a single mitochondrion that flanks the nucleus. Multiple acrosomal vesicles (three or four in number) are present at the apex of the sperm head in both species. Each vesicle is approximately 50 x 50 x 60 nm, and contains moderately electron-dense material. During spermiogenesis of A. zara, three or four vesicles appear in a blister of an early stage spermatid. These vesicles transform into multiple acrosomal vesicles without fusing with each other. Spermiogenesis and acrosome differentiation are similar in A. gemmata and A. zara. Three types of acrosome differentiation in ascidians are described.     

Polymerization of actin without acrosomal exocytosis in starfish sperm : Visualization with NBD-phallacidin

Polymerized actin sperm of the starfish Pisaster ochraceus is stained intensely by NBD-phallacidin in the fluorescence microscope. Parallel phase contrast, Nomarski and scanning electron microscopy (SEM) illustrate other changes brought about in sperm treated with the calcium ionophore A23187 and NH₄Cl. A complete acrosome reaction is elicited by A23187, including exocytosis of the acrosomal vesicle and formation of a long acrosomal process which is filled with polymerized actin. Considerable actin polymerization is caused by NH₄Cl, but the acrosomal vesicle is not exocytosed. The various patterns of NH₄Cl-mediated polymerization of sperm actin always include bundles which project backward from the actomere and often others which project quite far forward in front of the acrosomal vesicle. These patterns are discussed in terms of the possible triggers and mechanisms of forming actin bundles in sperm.     

Acrosome reaction in spermatozoa from the amphioxus Branchiostoma belcheri (Cephalochordata, Chordata)

The formation of an acrosomal process at acrosomal exocytosis in spermatozoa of the amphioxus was described in the present report for the first time. A non-reacted acrosome was located in front of the nucleus, where a cup-shaped acrosomal vesicle covered a conical accumulation of subacrosomal material. When naturally spawned spermatozoa were treated with a calcium ionophore, ionomycin, the acrosomal vesicle opened at the apex and an acrosomal process was projected. The process exhibited a filamentous structure. The reaction followed the mode typically seen in marine invertebrates. These observations suggest that the features and function of the acrosome of amphioxus, whose position is on the border between invertebrates and vertebrates, reflect their ecological adaptation and phylogenic position.     

The Acrosome Reaction in Ciona intestinalis (Ascidia, Tunicata)

An acrosome reaction occurs by fusion between the acrosomal outer membrane and the plasmalemma enclosing the acrosome in Ciona intestinalis spermatozoa. The fusion seems to proceed along the peripheral margin of the acrosome, which causes vesiculation. The membrane bound vesicle formed by this process is probably shed by the sperm. The acrosomal inner membrane is exposed and becomes a part of the plasmalemma enclosing the anterior region of the sperm head. During this process, any acrosomal substance might be released through the opening formed by membrane fusion. The acrosome reaction most likely occurs in C. intestinalis spermatozoa, via vesiculation, in fundamentally the same way as observed in mammalian spermatozoa.     

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.     

Fine structure of the spermatozoa of Crassostrea gigas (Mollusca,Bivalvia)

We describe sperm ultrastructure and acrosome differentiation during spermiogenesis in Crassostrea gigas (Mollusca Bivalvia). The sperm cell is a uniflagellated cell of the primitive type. The head region contains a rounded or conical nucleus surmounted by small acrosome. This organelle consists of a membrane-bound acrosomal granule, the contents of which have a homogeneous density, except in the anterior region, which is positive for PTA. The acrosome also surrounds the perforatorium, which includes oriented fibrillar elements: this is the axial body. The middle piece contains four mitochondria encircling two perpendicular centrioles. The distal centriole is provided with a system of mechanical fixation to the plasma membrane, consisting of nine fibers in radial arrangement. The tail flagellum, about 50 m?m long, contains the usual microtubular axoneme. © 1993 Wiley-Liss, Inc.