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     

三疣梭子蟹精子的发生及超微结构研究

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     

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 spermatogenesis and spermatozoa of Cephalodasys maximus (Gastrotricha,Macrodasyida)

Summary Spermatogenesis and sperm ultrastructure of the macrodasyidan gastrotrich Cephalodasys maximus are described by means of transmission electron microscopy. The filiform sperm consists of an acrosomal accessory structure and an acrosomal vesicle, both being surrounded by spiralled material. The successive nuclear helix encloses the spiral-shaped mitochondrion and the axoneme of the flagellum is accompanied by dense strings, three helical elements and peripheral microtubules. During spermiogenesis the acrosomal accessory structure develops first and moves into a cell projection, where the spiral around this acrosomal rod forms. A nuclear section with condensed chromatin and one single fused large mitochondrion follow into the extension, becoming helical. A connecting clasp between nucleus and flagellum shortens to a cap-like structure. Parallel to the acrosomal and nuclear projection the flagellum develops where the spiralled elements and the basal plate form in succession, while the basal body shrinks.     

ELECTRON MICROSCOPE STUDIES ON SPERM DIFFERENTIATION IN MARINE ANNELID WORMS. I. SPERM FORMATION IN IKEDOSOMA GOGOSHIMENSE

The ultrastructur of spermatozoa and the changes through which they are differentiated during sperm formation in an echiuroid were observed under the electron microscope. Many spermatids are connected to one central cytoplasmic mass and the sperm differentiation proceeds synchronously in one sperm-ball. Dense plate-like structures appear in the cytoplasm of early spermatids and disappear soon. In the process of nuclear condensation, many electron-dense aggregates appear in homogeneously textured chromonema and the aggregates are packed together to form a uniformly dense nucleus. Near the centriole at the opposite side from the central mass, the mitochondria fuse together to form one large middle-piece mitochondrion and the acrosomal vesicle is formed from the Golgi-complex. The differentiating acrosome in the late spermatid moves to the anterior tip of the head. In the completed acrosome, a flocculent substance accumulates in the conspicuously expanded invaginated pocket of the acrosomal vesicle and two kinds of material of different electron density fill the inside of the acrosomal vesicle. The spermatozoa remain connected to the central mass at the lateral side of the head until they become fully mature and are packed into the nephridia before spawning.     

锯缘青蟹精子发生的超微结构

采用透射电镜观察锯缘青蟹精子发生过程中超微结构的变化,结果表明：精原细胞椭圆形,染色质分布于核膜周围,胞质中具嵴少的线粒体,内质网小泡等。初级精母细胞染色质呈非浓缩状,胞质中具众 内质网小泡,特殊的膜系及晶格状结构。次级精母细胞核质间出现由内质小泡聚集成的腔。     

Spermiogenesis in the Marine Shrimp, Sicyonia ingentis

Spermiogenesis in the marine prawn Sicyonia ingentis was examined using transmission electron microscopy. The acrosomal vesicle, derived from the fusion of pro-acrosomal vesicles blebbed from the nuclear envelope, contains the membrane pouches, anterior granule and a spike. The anterior granule is formed from the coalescence of granular aggregates within the proacrosomal vesicles. Primordia underlying the apical acrosomal vesicle membrane polymerize to form a spike approximately 6 μm long. The convoluted pouch membranes arise from the posterior acrosomal vesicle membrane. Lateral and apical portions of the acrosomal vesicle are surrounded by a pentalaminar membrane comprised of the spermatid plasma membrane and the acrosomal vesicle membrane. Subacrosomal structures include the dense saucer plate, granular core and crystalline lattice. These components condense just posterior to the acrosomal vesicle and are separated from the chromatin by a nuclear plate.
The spermatid nucleus becomes surrounded by rough endoplasmic reticulum (RER) and membranous lamellar bodies. RER gives rise to smooth endoplasmic reticulum. These membrane systems degenerate, forming a band of reticular elements around the lateral and posterior portions of the nucleus. The nucleus undergoes condensation followed by decondensation with concomitant breakdown of the nuclear envelope. The resultant chromatin is fibrillar in appearance.     

Ultrastructural study of spermiogenesis in a rare desert amphisbaenian Diplometopon zarudnyi

Spermiogenesis, in particular the head differentiation of Diplometopon zarudnyi, was studied at the ultrastructural level by Transmission Electron Microscope (TEM). The process includes acrosomal vesicle development, nuclear elongation, chromatin condensation and exclusion of excess cytoplasm. In stage I, the proacrosomal vesicle occurs next to a shallow fossa of the nucleus, and a dense acrosomal granule forms beneath it. This step commences with an acrosome vesicle forming from Golgi transport vesicles; simultaneously, the nucleus begins to move eccentrically. In stage II, the round proacrosomal vesicle is flattened by projection of the nuclear fossa, and the dense acrosomal granule diffuses into the vesicle as the fibrous layer forms the subacrosomal cone. Circular manchettes surrounded by mitochondria develop around the nucleus, and the chromatin coagulates into small granules. The movement of the nucleus causes rearrangement of the cytoplasm. The nucleus has uniform diffuse chromatin with small indices of heterochromatin. The subacrosome space develops early, enlarges during elongation, and accumulates a thick layer of dark staining granules. In stage III, the front of the elongating nucleus protrudes out of the spermatid and is covered by the flat acrosome; coarse granules replace the small ones within the nucleus. One endonuclear canal is present where the perforatorium resides. In stage IV, the chromatin concentrates to dense homogeneous phase. The circular manchette is reorganized longitudinally. The Sertoli process covers the acrosome and the residues of the cytoplasmic lobes are removed. In stage V, the sperm head matures.     

Structural changes in sperm from the fiddler crab, Uca tangeri (Crustacea, Brachyura), during the acrosome reaction.

The acrosome reaction (AR) was induced in sperm from the brachyuran crustacean Uca tangeri either by mixing male and female gametes in filtered seawater or by treating the spermatozoa with the divalent cation ionophore A23187. This latter method provided a sufficient number of reacted spermatozoa to allow a detailed ultrastructural study of the AR. The process consists of two separate phases: a) initial release of the acrosomal vesicle contents, and b) further elongation of the acrosomal filament, which causes reversal of the rigid capsule limiting the acrosomal vesicle contents. The elongate acrosomal filament consists of an apical perforatorium and a basal columnar structure called here the proximal piece. The former derives from the perforatorium of the uninduced sperm stage with only small ultrastructural changes. The proximal piece forms from myelin-like membrane layers which are initially distributed all around the subacrosomal region and then accumulate in a column at the perforatorial base, thus promoting a sudden forward projection of the perforatorium. The AR in brachyurans is thought to be a passive mechanism that utilizes the negative pressure exerted on the nucleus--caused by emptying of the acrosomal vesicle--for an organized accumulation of membrane-rich material immediately behind the perforatorium, with the final result of the raising of a 3 microns long acrosomal filament.     

The Multi-PDZ domain protein MUPP1 as a lipid raft-associated scaffolding protein controlling the acrosome reaction in mammalian spermatozoa

The success of acrosomal exocytosis, a complex process with a variety of interrelated steps, relies on the coordinated interaction of participating signaling molecules. Since scaffolding proteins are known to spatially organize sequential signaling pathways, we examined whether the Multi-PDZ domain protein MUPP1, recently identified in mammalian spermatozoa, is functionally active in controlling acrosomal secretion in mammalian sperm cells. To address this question, permeabilized mouse sperm were loaded with inhibitory antibodies against MUPP1 as well as with a photosensitive Ca(2+) chelator which allows a controlled release of acrosomal Ca(2+). The results revealed that MUPP1 controls initial tethering and docking of the acrosomal vesicle, whereas syntaxin 2, a t-SNARE protein also expressed in the acrosomal cap of mammalian spermatozoa, appears to take part in the final process of acrosomal fusion. Interestingly, using immunogold electron microscopy, it was found that MUPP1 is detectable in the region of the periacrosomal membrane. Furthermore, in isolated detergent-insoluble glycolipid-enriched membrane domains from epididymal spermatozoa, MUPP1 was found to show a striking association with the Triton X-100 insoluble membrane fraction, which did not change significantly upon sperm capacitation or partial chemical extraction of cholesterol. This evidence points to a role of MUPP1 as a membrane raft-associated molecular organizer, and suggests that mammalian spermatozoa may use a scaffolding protein and distinct membrane subdomains to spatially organize components involved in the process of acrosomal exocytosis.     

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。     

Comparative study of sperm ultrastructure of Donax hanleyanus and Donax gemmula (Bivalvia: Donacidae)

The ultrastructure of bivalve spermatozoa can be species‐specific and often provides important taxonomic traits for systematic reviews and phylogenetic reconstructions. Young individuals of the Donacidae species Donax hanleyanus are often identified as samples of Donax gemmula. Hence, the spermatozoa ultrastructure of both species was described in the present work, aiming to identify characters that could be useful for further taxonomic and phylogenetic analyses. D. hanleyanus and D. gemmula spermatozoa were different especially in relation to acrosomal characteristics and chromatin condensation. The spermatozoon produced by D. hanleyanus had a nucleus (exhibiting granular chromatin with a rope‐like appearance) capped by a long and conical acrosomal vesicle, which extended itself outward beyond the anterior nuclear fossa. Otherwise, the nucleus of the sperm cell of D. gemmula showed well‐compacted chromatin, and its acrosome, which was partially inserted into the anterior nuclear fossa, had a bubble‐like tip. In conclusion, the conspicuous ultra‐structural differences found between the spermatozoan morphologies were helpful for the discrimination of the species. In conclusion, our results suggest that analyses of sperm ultrastructure of the bivalves in the family Donacidae can be valuable to investigate their taxonomic relatedness. The present results also contribute to assess the monophyletic status of the family.     

蟹类精子超微结构的比较研究

应用光镜和电镜,比较研究了三疣梭子蟹,中华绒螯蟹和长江华溪蟹的成熟精子。揭示３种蟹精子都是不能游动的无鞭毛精子,呈球形,前后略扁,精子前端出现一光滑的小圆面,圆面四周有内陷的沟环。沟环之后,精子表面凹凸不平,并伸出多数辐射臂。３种蟹精子均为高度特化的细胞,外被质膜,内含细胞核,顶体及退化的细胞质。     

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.     

Fine structure distribution of non-specific acid phosphatase in the head region of mouse spermatozoa from various regions of the male reproductive tract.

The fine structure distribution of non-specific acid phosphatase was determined in the head region of mouse spermatozoa from the testes, the caput, corpus and cauda epididymidis and the ductus deferens. Enzymatic localization was achieved by the Gomori technique. The postacrosomal dense lamina, the nuclear side of the inner acrosomal membrane and the space between the plasmalemma and the outer acrosomal membrane showed reaction product in spermatozoa from the testis and caput epididymidis. Spermatozoa from the cauda epididymidis exhibited reaction product only between the plasmalemma and the outer acrosomal membrane. Spermatozoa from the corpus epididymidis and from the ductus deferens showed no reaction product in the head region. The changes observed in the distribution of acid phosphatase in the sperm head during epididymal transport may reflect maturational events.     

A comparative ultrastructural analysis of spermatozoa in Pleurodema (Anura,Leptodactylidae, Leiuperinae)

This study describes the spermatozoa of 10 of the 15 species of the Neotropical frog genus Pleurodema through transmission electron microscopy. The diversity of oviposition modes coupled with a recent phylogenetic hypothesis of Pleurodema makes it an interesting group for the study of ultrastructural sperm evolution in relation to fertilization environment and egg‐clutch structure. We found that Pleurodema has an unusual variability in sperm morphology. The more variable structures were the acrosomal complex, the midpiece, and the tail. The acrosomal complex has all the structures commonly reported in hyloid frogs but with different degree of development of the subacrosomal cone. Regarding the midpiece, the variability is given by the presence or absence of the mitochondrial collar. Finally, the tail is the most variable structure, ranging from single (only axoneme) to more complex (presence of paraxonemal rod, cytoplasmic sheath, and undulating membrane), with the absence of the typical axial fiber present in hyloid frogs, also shared with some other genera of Leiuperinae. J. Morphol. 277:957–977, 2016. © 2016 Wiley Periodicals, Inc.     

Localization of intracellular calcium during the acrosome reaction in ram spermatozoa

Calcium was identified by a pyroantimonate-osmium fixation technique in ram spermatozoa undergoing a spontaneous acrosome reaction induced by incubation of diluted semen at 39°C. Intracellular calcium was only detected in diluted spermatozoa and increased in amount and distribution over 4 hr At 4 hr, the majority of the spermatozoa displayed ultrastructural evidence of an acrosome reaction. Calcium was initially evident on the outer acrosomal membrane in multiparticulate clusters, which were seen to be located on scalloped crests of acrosomal membrane as fusion developed; it was also located in the region of the acrosomal ridge beneath the outer acrosomal membrane. Vesiculation commenced just anterior to the equatorial segment and proceeded anteriorly. As vesiculation advanced, calcium particles became associated with the periphery of the vesicles attached in the region of the fusion between the two membranes, but were never seen inside the vesicles. The equatorial segment was not labelled until much later in the reaction, at which time calcium particles were also evident on the nuclear membrane; vesiculation of the equatorial segment was also noted at this time. Dense labelling of the postacrosomal dense lamina was seen in all incubated spermatozoa. At the anterior margin of this structure the labelling was seen to be in a “sawtooth” arrangement. The disposition of the calcium both temporally and spatially is discussed in relation to its possible mechanisms in bringing about membrane fusion. © 1995 Wiley-Liss, Inc.     

Spermatogenesis and ultrastructure of the spermatozoa of Seison nebaliae (Syndermata)

 The spermatozoa of Seison nebaliae are characterized by an elongated sperm body, a filiform nucleus, and an anteriorly inserting external cilium with a 9×2+2 axoneme pattern. In the sperm body a frontal, middle, and hind region can be distinguished. The frontal region contains an acrosomal vesicle, a perforatorium, a basal body, and a pair of apical dense bodies; an accessory centriole is absent. The middle region is characterized by several so-called filamental plates. One large mitochondrion and one pair of accessory tubular structures are located in the middle and hind region. The hind region also contains two rows of dense bodies. Accessory tubular structures and filamental plates are autapomorphies of S. nebaliae. The shared appearance of the dense bodies in spermatozoa of species of the taxa Seison and the Acanthocephala founds their sister-group relationship, while the anterior insertion of the cilium in the spermatozoa of these taxa and in the Rotifera confirms the monophylum Syndermata Ahlrichs, 1995. Accepted: 5 August 1998     

ZYGOTE FORMATION IN ASCARIS LUMBRICOIDES (NEMATODA)

Ultrastructural observations of the in utero sperm of Ascaris lumbricoides reveal that it consists of a relatively clear, ameboid anterior region and a conical posterior region containing numerous surface membrane specializations, dense mitochondria, a lipid-like refringent body of variable size, and a dense nucleus which lacks an apparent nuclear envelope. No acrosomal complex was observed. Pseudopods emanating from the anterior cytoplasm make first contact with the primary oocytes and appear to be responsible for the localized removal of the extraneous coat covering the oolemma. Subsequently the gamete membranes interdigitate and finally fuse. Because this pseudopodial action appears similar to that reported for the acrosomal filaments in flagellated sperm, the anterior region of the Ascaris sperm is thought to serve an acrosomal function. Following gamete-membrane fusion, the sperm nucleus acquires a particulate appearance and becomes disorganized. Once inside the oocyte, the sperm cytoplasm consists of dense mitochondria, ribosomes, and vesicles derived from the surface membrane specializations. The refringent body, whose contents possibly contribute to the synthesis of ribosomes, is usually absent by the time the sperm cytoplasm attains a central position in the egg.