A study of intercellular bridges during spermatogenesis in the rat

A morphological evaluation of intercellular bridges was undertaken during rat spermatogenesis. The dimensions and relationships of the bridges were shown to vary during different phases of spermatogenesis. Cellular divisions of spermatogonia and spermatocytes resulted in the partitioning of pre-existing bridges by complex structures termed bridge partitioning complexes, which are described in detail, as is the process whereby new bridges are formed. The structure of premeiotic bridges was generally consistent; however, during spermiogenesis, the structure of bridges and bridge contents were modified at specific phases of their development. The plasma membrane density associated with the cytoplasmic aspect of early step 1 spermatids separated into multiple dense bands that encircled the peripheral aspect of late step 1 spermatid bridges. By step 2 of spermiogenesis, these dense bands became associated with several cisternae of endoplasmic reticulum, which later coalesced into a single saccule that completely encircled the bridge structure by step 4. At steps 10-13 of spermiogenesis, the single saccule of endoplasmic reticulum vesiculated into many smaller cisternae. Also, filament-bounded densities (measuring 10-12 nm in diameter) appeared within the bridge channel. At step 17 of spermiogenesis, the filament-bounded densities were no longer apparent, but an anastomosing network of endoplasmic reticulum, often in the configuration of a sphere, occupied the entire central region of the bridge. In step 19 spermatids, the smooth endoplasmic reticulum within the bridge channel and the multiple cisternae lining the bridge density were gradually displaced. The subsurface density of bridges gradually lost its prominence. Some cytoplasmic lobes were connected by extremely narrow (approximately 22 nm) cytoplasmic channels. Similar-appearing channels were seen on the surface zone of cytoplasmic lobes or residual bodies, this observation suggesting that channels were sites of severence of bridges. Just prior to the separation or disengagement of the spermatid from the cytoplasmic lobe, selected bridges appeared to open to form large masses. After spermiation, residual bodies were not found joined by bridges; but from the size of some of the residual bodies, it was suspected that they were formed by coalescence of more than one cytoplasmic lobe. Freeze-fracture demonstrated few intramembranous particles on either the P or E face of the plasma membrane forming the bridge; this finding suggested bridge structures restricted free lateral movement of membrane constituents across the bridge.(ABSTRACT TRUNCATED AT 400 WORDS)     

Ultrastructural study of spermatogenesis in Oscarella lobularis (Porifera,Demospongiae)

Summary

The various phases of spermatogenesis in the demosponge Oscarella lobularis were studied by electron microscopy. Spermatogenesis occurs within spermatic cysts, which are presumed to derive from choanocyte chambers by transformation of choanocytes into spermatogonia. Germ cells develop asynchronously within spermatocysts, and cytoplasmic bridges, indicating incomplete cells division, connect several germ cells. Attached spermatogonia suggest gonial generations. Spermatocytes I typically show the presence of synaptonemal complexes indicating meiotic divisions. Spermatocytes II have a small size probably because of the meiotic divisions of spermatocytes I. Spermatids are characterized by an acrosome, a big mitochondrion and a peripheral sheath of condensed chromatin surrounding a clearer central area in the nucleus. The mature spermatozoon shows a lateral flagellum and a flattened acrosome capping the nucleus. The phylogenetic implications of some features of the spermatozoon are suggested.     

Ultrastructural demonstration of the model of Litopenaeus vannamei (Crustacea,Penaeidae) male sexual maturation and spermatozoal capacitation

The present study demonstrates ultrastructurally the model of Litopenaeus vannamei male sexual maturation and spermatozoal capacitation. The results show that phase 1 of the model occurred in the seminiferous tubules and includes spermatogenesis. In this phase, throughout differentiation of spermatogonia into late spermatids the following processes were observed: (1) decondensation of chromatin; (2) rupture of the nuclear envelope; (3) reduction of the cytoplasm and degeneration of organelles; (4) formation of the acrosome via fusion of cytoplasmic vesicles. Phase 2 comprised of spermatozoal maturation, a process that started with the transfer of late spermatids into the seminiferous ducts and ended with the formation of the acrosomal spike in the terminal ampoules. During this phase, development of the subacrosomal region and lateral electron-dense particles occurred in the seminiferous ducts, which is a novel finding of this species. Phase 3 was observed after spermatophore placement on the female thelycum and was mainly characterized by ultrastructural changes in the nucleus and the subacrosomal region. These results are in agreement with the model of male sexual maturation and spermatozoal capacitation proposed for L. vannamei.     

Ultrastructure of the testis in Synbranchus marmoratus (Teleostei,Synbranchidae): the germinal compartment

Synbranchus marmoratus, is a protogynic diandric species in which two types of males, primary and secondary, are found. In both types, the germinal compartment in the testes is of the unrestricted lobular type, but in secondary (sex reversed females) males the lobules develop within the former ovarian lamellae. In the present study, the germinal compartment was examined in both types of males using light microscopy as well as scanning and transmission electron microscopy. Germinal compartment is limited by a basement membrane and contains Sertoli and germ cells. During maturation, processes of Sertoli cells form the borders of spermatocysts containing isogenic germ cells. Characteristically, type A and type B spermatogonia have a single nucleolus and grouped mitochondria associated with dense bodies or nuage. Type B spermatogonia, spermatocytes and spermatids are joined by cytoplasmatic bridges and are confined within spermatocysts. Secondary spermatocytes are difficult to find, indicating that this stage is of short duration. Biflagellated spermatozoa have a rounded head, no acrosome, and possess a midpiece consisting of two basal bodies, each of which produces a flagellum with a typical 9+2 microtubular composition. No associations occur between sperm and Sertoli cells. There were no differences between spermatogenesis in primary and secondary males in this protogynic, diandric fish.     

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.     

Spermiogenesis and spermatozoa in Acanthodasys aculeatus (Gastrotricha, Macrodasyida): an ultrastructural study

The spermatogenesis, the spermiogenetic process and the structure of the mature spermatozoon of Acanthodasys aculeatus (Gastrotricha, Macrodasyida) are described from an ultrastructural point of view. Several spermatogonia in mitotic divisions were seen, proving that euthely of gastrotrichs does not concern gonads. Spermiogenesis is characterized by the early formation of both the acrosome and the axoneme, by the subsequent appearances of a perinuclear helix and of a complex axial tubular structure in the acrosome and by the late development of the peraxonemal striated cylinder. The mature spermatozoon is filiform, and composed of a spiralized acrosome, a helical nuclear–mitochondrial complex and a long flagellum. The acrosome contains an axial tubular structure and the spring-shaped nucleus delimits a single, long mitochondrion. A perinuclear helix formed by the pro-acrosome surrounds the nuclear–mitochondrial complex extending for its whole length. A monolayered, obliquely striated cylinder encloses the 9 × 2 + 2 axoneme; its terminal part is empty because of the shortness of the axoneme.     

Ultrastructure of spermatogenesis and mature spermatozoa in the flatworm Prosthiostomum siphunculus (Polycladida,Cotylea)

This is the first study investigating spermatogenesis and spermatozoan ultrastructure in the polyclad flatworm Prosthiostomum siphunculus. The testes are numerous and scattered as follicles ventrally between the digestive ramifications. Each follicle contains the different stages of sperm differentiation. Spermatocytes and spermatids derive from a spermatogonium and the spermatids remain connected by intercellular bridges. Chromatoid bodies are present in the cytoplasm of spermatogonia up to spermatids. During early spermiogenesis, a differentiation zone appears in the distal part of spermatids. A ring of microtubules extends along the entire sperm shaft just beneath the cell membrane. An intercentriolar body is present and gives rise to two axonemes, each with a 9 + “1” micro‐tubular pattern. Development of the spermatid leads to cell elongation and formation of a filiform, mature spermatozoon with two free flagella and with cortical microtubules along the sperm shaft. The flagella exit the sperm shaft at different levels, a finding common for acotyleans, but so far unique for cotylean polyclads. The Golgi complex produces numerous electron‐dense bodies of two types and of different sizes. These bodies are located around a perinuclear row of mitochondria. The elongated nucleus extends almost along the entire sperm body. The nucleus is wide in the proximal part and becomes narrow going towards the distal end. Thread‐like chromatin mixed with electron‐dense intranuclear spindle‐shaped bodies are present throughout nucleus. The general sperm ultrastructure, the presence of intranuclear bodies and a second type of cytoplasmic electron‐dense bodies may provide characters useful for phylogenetic analysis.     

Characterization of two antigenically related integral membrane proteins of the guinea pig sperm periacrosomal plasma membrane

The periacrosomal plasma membrane of mammalian spermatozoa functions both in recognition and in binding of the egg's zona pellucida and in the acrosome reaction. This study characterizes two antigenically related proteins with molecular weights of 35 kD (PM35) and 52 kD (PM52) of the guinea pig sperm periacrosomal plasma membrane. Polyclonal antisera were prepared against electrophoretically purified PM35 or PM52. Each antiserum recognized both the 35-kD and 52-kD polypeptides on Western blots, indicating that they are structurally related. This conclusion was supported by peptide mapping experiments demonstrating comparably sized fragments of both PM35 and PM52. Both PM35 and PM52 behave as integral membrane proteins during phase-separation analysis with Triton X-114. Electron microscopic immunocytochemistry and differential fractionation of sperm membranes established that both PM35 and PM52 are exclusively localized to the periacrosomal plasma membrane. Three different antisera were used for ultrastructural studies, and each specifically bound the cytoplasmic but not the extracellular membrane surface. The electrophoretic mobilities of the PM35 and PM52 polypeptides were unchanged during sperm maturation and during the ionophore-induced acrosome reaction. The localization of PM35 and PM52 suggests a potential role for these integral plasma membrane proteins in signal transduction or membrane fusion events of the acrosome reaction. © 1994 Wiley-Liss, Inc.     

线粒体可能参与鲫鱼精子发生中拟染色体的形成

运用电子显微镜观察了鲫鱼生精细胞发育过程中拟染色体的形成和解体,以及拟染色体和线粒体的关系。在精子细胞阶段之前的各期生精细胞中都存在拟染色体。仅在精原细胞中观察到拟染色体的形成过程。拟染色体的形成方式与其它鱼类中拟染色体的形成方式相似。在生精细胞的发育过程中,线粒体的形态和数量发生变化。在初级精原细胞阶段,线粒体较大,多为球形,嵴少,基质电子密度低。随着生精细胞的发育,线粒体逐渐变小,多为长条状,嵴多,基质的电子密度升高。拟染色体形成后往往与线粒体结合。与拟染色体结合的线粒体往往解体,部分或全部的外膜和内膜破裂以至消失。线粒体解体后,其中的物质可能会转移到拟染色体中[动物学报52(2):328-334,2006]。     

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.     

Nuclear and cytoplasmic differentiation in developing sperm of the crayfish,Cambaroides japonicus

Summary In the present electron microscopic study of spermatogenesis in the crayfish, Cambaroides japonicus, it was possible to clarify several aspects of the unusual differentiation which leads to the production of an aflagellate sperm. The centriole is followed from the metaphase of the second spermatocyte division to the time at which, in the nearly mature sperm, it appears to disintegrate. It has no connection with the acrosome but in the late spermatid and maturing sperm it is found randomly oriented among the convoluted membranes of the filamentous endoplasmic reticulum.There appears to be a close association of mitochondria with the developing acrosomal vesicle. Typical mitochondria, however, are not present after the late spermatid stage of development. It is suggested that the complex lamellar bodies associated with the nuclear envelope in the late stages of spermatogenesis may be related to mitochondria for these lamellar bodies resemble the complex mitochondria found in the adjacent nutritive cells.The development of the acrosome has been traced from an aggregate of dense granules which first appear in the interzonal spindle region and are later segregated at one side of the cell after the second spermatocyte division. As differentiation proceeds, tubular elements appear and disappear within the acrosome, while somewhat later, fibrous elements appear in the matrix. In the mature acrosome, the fibrous elements remain only adjacent to the granular periphery of the acrosome and the core again becomes homogeneous.No typical Golgi complex is found in these cells at any time during their differentiation.In the maturing sperm the development of the arms of the nucleus was studied. Preceding the differentiation of the arms a coarse fibrous material develops in the periphery of the nucleus. It is shown that the fibrillar material in the matrix of the arms is in continuity with the fibrillar material in the matrix of the nucleus proper.Supported in part by Grant No. B 2314 of the National Institute of Neurological Diseases and Blindness, U.S. Public Health Service.Predoctoral Research Fellow of the National Institute of Neurological Diseases and Blindness, U.S. Public Health Service.     

Spermatogenesis of the spider crab Maja brachydactyla (Decapoda: Brachyura)

This study describes spermatogenesis in a majid crab (Maja brachydactyla) using electron microscopy and reports the origin of the different organelles present in the spermatozoa. Spermatogenesis in M. brachydactyla follows the general pattern observed in other brachyuran species but with several peculiarities. Annulate lamellae have been reported in brachyuran spermatogenesis during the diplotene stage of first spermatocytes, the early and mid‐spermatids. Unlike previous observations, a Golgi complex has been found in mid‐spermatids and is involved in the development of the acrosome. The Golgi complex produces two types of vesicles: light vesicles and electron‐dense vesicles. The light vesicles merge into the cytoplasm, giving rise to the proacrosomal vesicle. The electron‐dense vesicles are implicated in the formation of an electron‐dense granule, which later merges with the proacrosomal vesicle. In the late spermatid, the endoplasmic reticulum and the Golgi complex degenerate and form the structures–organelles complex found in the spermatozoa. At the end of spermatogenesis, the materials in the proacrosomal vesicle aggregate in a two‐step process, forming the characteristic concentric three‐layered structure of the spermatozoon acrosome. The newly formed spermatozoa from testis show the typical brachyuran morphology. J. Morphol., 2010. © 2009 Wiley‐Liss, Inc.     

Selective partitioning of plasma membrane antigens during mouse spermatogenesis

The selective partitioning of cell membrane components during mouse spermatogenesis has been examined using a heterologous antibody raised against isolated type B spermatogonia. The anti-type B spermatogonia rabbit IgG (ATBS) binds to isolated populations of mouse primitive type A spermatogonia, type A spermatogonia, type B spermatogonia, preleptotene spermatocytes, leptotene/zygotene spermatocytes, pachytene spermatocytes, round spermatids, residual bodies, and mature spermatozoa. Although immunofluorescent labeling is uniformly distributed on the cell surface of early spermatogenic cells, a discrete topographical localization of IgG is observed on testicular, epididymal, and vas deferens spermatozoa. The convex surface of the acrosome, postacrosomal region, and tail are labeled. Antibody does not bind to a broad area corresponding to the concave region of the acrosome. The antibody also binds to mouse somatic cells including Sertoli cells, Leydig cells, thymocytes, and splenocytes, but not to mature spermatozoa of the vole, rat, hamster, guinea pig, rabbit, or human. ATBS, after absorption with mouse splenocytes or thymocytes, does not react with any somatic cells examined by fluorescence except with Sertoli cells. In addition, all reactivity with testicular, epididymal, and was deferens spermatozoa is abolished. However, spermatogenic cells at earlier stages of differentiation, including residual bodies, still react strongly with the absorbed antibody. The number of surface receptor sites per cell for absorbed ATBS ranges from approximately 3 million on primitive type A spermatogonia to 1 million on round spermatids and on residual bodies. Spermatozoa, however, have only 0.003 million binding sites for absorbed ATBS, in contrast to 10 million sites for the unabsorbed antibody. It appears that receptor sites for absorbed ATBS are not masked by components of epididymal secretions. These data imply, therefore, that specific mechanisms operate at the level of the cell membrane during spermiogenesis to insure that some surface components, not required in the mature spermatozoon, are removed selectively by partitioning to that portion of the spermatid membrane destined for the residual body.     

大熊猫精子获能和顶体反应过程中钙分布变化规律的研究

应用焦锑酸钾原位定位法对大熊猫精子获能和顶体反应过程中进行钙定位研究,发现未获能精子的 Ｃａ２＋主要结合于顶体前区和赤道段质膜外侧和顶体内膜内侧（核膜侧）;随着获能的进行,Ｃａ２＋进入精子内部并主要结合于顶体区质膜内侧和顶体外膜外侧;顶体反应的精子,Ｃａ２＋结合于顶体内膜外侧、顶体后区质膜外侧和分散存在于释放的顶体内容物中,有些顶体反应精子的顶体内膜外侧结合的Ｃａ２＋特别丰富。精子尾部的Ｃａ２＋主要分布于中段线粒体内,且其内所含Ｃａ２＋含量随着获能和顶体反应而增加。另外尾部致密纤维和轴丝处也有少量Ｃａ２＋分布。     

Acrosomal reaction and early events at fertilization in Marthasterias glacialis (Echinodermata: Asteroidea)

When the spermatozoon of M glacialis contacts the mature oocyte jelly it adheres to it. Following this, there is a slight tumefaction of the acrosome, which is followed by the disruption of the apical acrosomal vesicle and cytoplasmic membranes. Acrosomal vesicle contents are liberated and spread along the outer surface of the oocyte jelly. Meanwhile, the acrosomal process begins to extend, penetrates all the jelly extension, then the vitelline layer, and finally contacts the cytoplasmic egg membrane. Nevertheless, the sperm cell continues lying at the outer border of the jelly. From the beginning of the acrosome reaction the dense and finely fibrillar subacrosomal material is connected, by some expansions, to the basal acrosomal vesicle membrane. Both nuclear and mitochondrial diameters have diminished.     

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.     

Ultrastructural changes in the spermatogonia and spermatocytes of Poecilia reticulata during spermatogenesis

Summary The structure of guppy (Poecilia reticulata) spermatogonia and spermatocytes has been studied using electron microscopy. The spermatogonia, situated at the apex of the seminiferous tubule, are almost all surrounded by a network of Sertoli cells; they have very diffuse chromatin and one or two large nucleoli. The cytoplasm contains relatively few organelles, although annulate lamellae are found. The mitochondria have few cristae and are concentrated at one pole of the cell; they are sometimes found with intermitochondrial cement. These spermatogonia are separated from each other, having no intercellular bridges or inclusion in Sertoli cells, and are relatively undifferentiated; they correspond to stem cells. The spermatogonia beneath the apex are organized into cysts. First-generation spermatogonia are more dense and heterogeneous, their nuclei becoming smaller and their chromatin becoming denser during successive generations. In spermatocytes, the synaptinemal complex exists as a modified form until metaphase. The concentration of organelles in the cytoplasm increases and the organelles become more diversified as spermatogenesis progresses. Many cytoplasmic bridges are observed (several per cell), indicating that the cells remain in contact after several divisions. These changes in germ cell structure have been related to some of the characteristic features of spermatogenesis in guppy, e.g. the large number of spermatogonial generations and the complexity of spermiogenesis.     

Ultrastructural Study of Spermatogenesis and Mature Spermatozoa of Paravortex cardii (Platyhelminthes, Dalyellioida)

The spermatogenesis and mature spermatozoon of Paravortex cardii were studied by transmission electron microscopy. Meiotic divisions occur without cytokinesis and the spermatid nuclei appear embedded in a common cytoplasmic mass. The mature spermatozoon is filiform, very regular in contour and circular in cross-section. A tubular lining of microtubules lying close to the plasma membrane is found along the spermatozoon. Rows of spherical glycogen particles with helical arrangement lay internal to the cortical microtubules. The spermatozoon of P. cardii may be divided into two regions, nuclear and cytoplasmic regions. The nuclear region contains an elongated nucleus with a densely packed nuclear material. The mitochondria are distributed throughout the cytoplasmic region; they pack tightly together and often fuse to form one large one. This spermatozoon lacks both acrosome and the so-called dense bodies. A ciliary or centriolar apparatus was not observed. Accordingly, the spermatozoon of P. cardii is considered to be aflagellate in type. Spermatozoa are compared among flatworms, and some considerations on the significance of their ultrastructure for phylogeny in the Platyhelminthes are tentatively given.     

KIFC1 participates in acrosomal biogenesis, with discussion of its importance for the perforatorium in the Chinese mitten crab Eriocheir sinensis

Spermatogenesis is a complicated process during which spermatogonia undergo proliferation and divisions leading, after a series of dramatic changes, to the production of mature spermatozoa. Many molecular motors are involved in this process. KIFC1, a C-terminal kinesin motor, participates in acrosome biogenesis and nuclear shaping. We report here the expression profile of KIFC1 during spermatogenesis in the Chinese mitten crab, Eriocheir sinensis. KIFC1 mainly localizes around the nucleus but is also present within the nucleus of the spermatogonium and spermatocyte. At the early spermatid stage, KIFC1 begins to be distributed on the nuclear membrane at the region where the proacrosomal vesicle is located. By the late spermatid stage, KIFC1 is found on the acrosome. Immunocytochemical and ultrastructural analyses have shown that KIFC1 localizes on the perforatorium, which is composed of an apical cap and an acrosomal tubule. We demonstrate that, during spermatogenesis in E. sinensis, KIFC1 probably plays important roles in the biogenesis of the acrosome and in its maintenance. KIFC1 may also be essential for the eversion of the acrosome during fertilization. This work was supported in part by the following projects: the National Natural Science Foundation of China (nos. 30671606 and 40776079) and the National Basic Research Program of China (973 Program; grant no. 2007CB948104).     

Binding of fluorescein isothiocyanate conjugated lectins to rat spermatogenic cells in tissue sections. Enhancement of lectin fluorescence obtained by fixation in Bouin's fluid

The testes from three months old Sprague-Dawley rats were fixed in Bouin's fluid or neutral buffered 10% formalin, embedded in paraffin, sectioned and after deparaffination stained with the following fluorescein isothiocyanate coupled lectins: PNA, WGA, Con A, RCA, SBA, DBA and UEA. The results show that there are considerable differences in the staining pattern of various spermatogenic cells between different lectins. The fixation in Bouin's fluid enhanced the staining of all the lectins compared to formalin fixation in which only a weak staining could be seen in the acrosomes of spermatids after WGA or PNA staining. PNA and WGA stained specifically the acrosome of the developing spermatids, which was seen from the beginning of the acrosome formation and lasted up to late spermiogenesis. However, the staining with PNA decreased in the late spermatids whereas the intensity of the staining remained unchanged with WGA. Con A did not stain the acrosome but stained unspecifically the cytoplasm of all spermatogenic cells. RCA stained faintly the acrosome throughout the spermatid differentiation. DBA and UEA stained specifically the chromosomes of B spermatogonia. DBA also faintly stained the cell membranes of early spermatids. SBA did not show any specific staining of the spermatogenic cells. Based on this it is suggested that the carbohydrates and glycoproteins which are known to be present in the acrosome are formed already in the beginning of the acrosome formation. The decrease in the PNA staining in late spermatids possibly reflects the fact that the receptor molecules are not synthesized in late spermatids but are formed in earlier developmental stages and are thereafter preserved in the acrosome.(ABSTRACT TRUNCATED AT 250 WORDS)