平疣桑椹石磺精子结构观察

通过电光学显微镜和透射电子显微镜观察了平疣桑椹石磺精子的形态及其超微结构。平疣桑椹石磺成熟精子属于进化型,由头部、中段和末段组成。头部由顶体和精核构成,顶体长约0.7μm,呈细奶嘴状,内含物分布均匀,电子密度稍低于细胞核。顶体基部与精核前端紧密相连,无间隙。精核长约3.8μm,宽约1.0μm,核质高度浓缩,电子密度高,无核泡,纵切似辣椒状,核后端内凹形成核后窝。中段加长,结构复杂,线粒体演化成线粒体鞘,螺旋状包绕轴丝。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。比较了平疣桑椹石磺精子与相关腹足类精子结构的异同,进一步证实了腹足纲贝类精子结构之间的区别主要在于顶体有无及形态,精核的长短与外形、中段线粒体的数目及其排列方式等。     

Spermatogenesis in the archaic hydrothermal vent bivalve,Bathypecten vulcani,and comparison of spermatozoon ultrastructure with littoral pectinids

Summary

Bathypecten vulcani is considered a relict species from the Paleozoic, based on shell characteristics such as the presence of calcite prisms. To date, it is the only pectinid species reported from hydrothermal ecosystems. Histological and ultrastructural studies show that spermatogenesis is identical to that of littoral pectinids. The spermatozoon has a 2.7 μm long pyriform head and a 40 μm flagellum. The four mitochondria of the mid-piece are about 1.2 μm in diameter. The nucleus contains dense chromatin fibres and possesses a wide, shallow (0.1 μm) anterior fossa and a narrow, deeper (0.2 μm) posterior nuclear fossa. Comparison of the ultrastructural characteristics of the spermatozoon of B. vulcani with those of littoral pectinids shows that they can be used as a diagnostic feature of this species. In particular, its acrosome characters will be a useful complement to the shell characters in the study of the phylogenetic position of this species in relation to other pectinids.     

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。     

鲤鱼精子超微结构的研究

鲤鱼精子由头部,中片和尾部组成,头部的细胞核卵形,染色质致密。核中有些小空隙,空中的电子致密物质存在。中片紧连在核的后端。中片由中心粒复合体和袖套组成。中心粒复合体位于核后植入窝中,袖套一侧肥厚,一侧狭窄,袖套中有线粒体和囊泡。囊泡有二类,一类含有电子致密物质;另一类无电子致密物质。近袖套内膜处的细胞质中还存在着与内膜平行的膜,精子尾部从袖套腔中伸出。尾部的轴丝与基体相接。尾部的近核端多有许多囊泡     

长吻鮠精巢及精子结构的研究

长吻鮠精巢高度分支呈指状。后1/3紫红色,由上皮细胞组成,既不产生精子,也不贮存精子。精巢的内部结构为叶型,由体细胞和生殖细胞构成,小叶的基本单位是小囊。精子头短而圆,主要为核占据,无顶体,核凹窝十分发达,有中心粒帽;尾极长,具侧鳍,轴丝基部有发达的囊泡状结构和线粒体。     

Identification of a male-specific (H-Y) antigen on the flagellar plasma membrane of ram epididymal spermatozoa

Summary H-Y (male-specific) antigen has been detected on the plasma membranes of both caput and caudal ram spermatozoa using both immunoperoxidase and immunofluorescence labelling techniques. In these spermatozoa the distribution of H-Y antigen appears to be confined to both the posterior region of the head and the mid-piece region of the flagellum. In addition, caput spermatozoa also exhibit intense immunoperoxidase staining of the cytoplasmic droplet which is situated on the flagellum at the base of the head. Western blot analyses of purified plasma membranes from the flagella of caudal spermatozoa have revealed the presence of a malespecific protein with an estimated molecular weight of 25,000–27,000.     

Spermatozoon structure of Acesta oophaga (Limidae), a cold-seep bivalve

The structure of the spermatozoon of Acesta oophaga (Bivalvia) is described by transmission electron microscopy. This cold-seep species produces ect-aquasperm, confirming that it is a broadcast spawner. The head of the sperm consists of a small, rounded, electron-dense nucleus, capped by a short conical acrosome, the contents of which are differentiated. The mid-piece contains a pair of orthogonally arranged centrioles surrounded by five spherical mitochondria. The gonad of one individual contained eggs and sperm, which supports the hypothesis that A. oophaga is a sequential hermaphrodite.     

Nicotinic acetylcholine receptor subunits and associated proteins in human sperm

We demonstrated previously the involvement of a nicotinic acetylcholine receptor containing an alpha7 subunit in the human sperm acrosome reaction (a modified exocytotic event essential to fertilization). Here we report the presence in human sperm of alpha7, alpha9, alpha3, alpha5, and beta4 nicotinic acetylcholine receptor subunits and the following proteins known to be associated with the receptor in the somatic cell: rapsyn and the tyrosine kinases c-SRC and FYN. The alpha7 subunit appears to exist as a homomer in the posterior post-acrosomal and neck regions of sperm and is probably linked to the cytoskeleton via rapsyn. The alpha3, alpha5, and beta4 subunits are present in the sperm flagellar mid-piece of sperm and possibly exist as alpha3alpha5beta4 and/or alpha3beta4 channels. The alpha9 subunit is present in the sperm mid-piece. We detected the FYN and c-SRC tyrosine kinases in the flagellar mid-piece region. Both co-precipitated only with the nicotinic acetylcholine receptor beta4 subunit. Immunolocalization with a C-terminal SRC kinase antibody, which recognizes several members of SRC kinase family, detected a SRC kinase co-localized with the alpha7 subunit in the neck region of sperm. Immunoprecipitation studies with that antibody demonstrated that the alpha7 subunit is associated with a SRC kinase. Antagonists of tyrosine phosphorylation inhibited the acetylcholine-initiated acrosome reaction, suggesting the involvement of a SRC kinase in the acrosome reaction.     

Morphology of the spermatozoon in two sympatric species of Fissurella Bruguière, 1789 (Mollusca: Vetigastropoda) from Southern Chile

Summary

Light and electron microscopy were used to analyze the morphology and ultrastructure of the spermatozoon of Fissurella nigra and Fissurella picta, two sympatric species of keyhole limpets from the southern Chilean coast. The spermatozoa of both species are of the aquasperm type, typical of species with external fertilization. Each species had its own distinctive spermatic morphology, particularly in relation to size. Proceeding from anterior to posterior, the spermatozoa of both species each consists of an elongated head with a conical acrosome having a deep subacrosomal space and truncated conical nucleus, followed by a midpiece containing five mitochondria associated in a compact ring around the proximal and distal centrioles, and, at the end, a flagellum. The spermatozoon head of F. nigra is almost twice as long as that of F. picta. This difference constitutes the first morphological evidence that the size of the spermatozoon could represent a candidate for the maintenance of reproductive isolation between these two sympatric species.     

Mammalian sperm morphometry.

Understanding the adaptive significance of sperm form and function has been a challenge to biologists because sperm are highly specialized cells operating at a microscopic level in a complex environment. A fruitful course of investigation has been to use the comparative approach. This comparative study attempts to address some fundamental questions of the evolution of mammalian sperm morphometry. Data on sperm morphometry for 445 mammalian species were collated from published sources. I use contemporary phylogenetic analysis to control for the inherent non-independence of species and explore relationships between the morphometric dimensions of the three essential spermatozoal components: head, mid-piece and flagellum. Energy for flagellar action is metabolized by the mitochondrial-dense mid-piece and these combine to propel the sperm head, carrying the male haplotype, to the ovum. I therefore search for evolutionary associations between sperm morphometry and body mass, karyotype and the duration of oestrus. In contrast to previous findings, there is no inverse correlation between body weight and sperm length. Sperm mid-piece and flagellum lengths are positively associated with both head length and area, and the slopes of these relationships are discussed. Flagellum length is positively associated with mid-piece length but, in contrast to previous research and after phylogenetic control, I find no relationship between flagellum length and the volume of the mitochondrial sheath. Sperm head dimensions are not related to either genome mass or chromosome number, and there are no relationships between sperm morphometry and the duration of oestrus.     

大黄鱼精子的超微结构

大黄鱼的精子由头产和尾部两部分组成。头部结构较为独特,其腹侧有一较大的细胞核,背部有中心粒复合体。头部的后端是袖套。细胞核的腹面稍向外突出背面则稍向内凹。细胞核中的染以质浓缩成致密的团块状。团块状的染色质之间分布着松散的纤维状染色质。植入窝位于细胞核的背部表面,由细胞核背面向内凹陷而成,呈一沟状,其走向与精子的长轴平行。     

Ultrastructure of spermatozoa of the lung fluke, Paragonimus ohirai (Trematoda: Troglotrematidae), in the seminal receptacle

The seminal receptacle of Paragonimus ohirai contains not only mature spermatozoa, but also atypical and degenerate ones, suggesting that abnormal spermatozoa are retained in this organ. The spermatozoon is of a parallel biflagellar type with cortical microtubules, consisting of the anterior region, first mitochondrial region, intermediate (amitochondrial) region, second mitochondrial region, posterior nuclear region (PNR) and tail region (TR). The first third of the spermatozoon exhibits typical undulatory movement, while the middle part shows vibratory movement. At the area between head and midsections (H-M area) the peripheral doublets of axonemes are interrupted, and the external ornamentation is distributed widely around this portion. Throughout the immotile PNR and TR, the axonemes lack the dynein arms of their peripheral doublets. H-M, PNR, and TR ultrastructural characteristics are specific in P. ohirai spermatozoon and seem to be closely related to its pattern of movement.     

The spermiogenesis and the early spermatozoa of <Emphasis Type="Italic">Armorloricus elegans</Emphasis> (Loricifera,Nanaloricidae)

The spermiogenesis consisting of five spermatid stages and the early spermatozoon has been investigated in Armorloricus elegans (Loricifera) with the use of transmission electron microscopy. The male reproductive system consists of three parts; testes, vasa deferentia and seminal vesicles. Caudally, the two seminal vesicles merge together in a ciliated duct and the excretory/gonadal—and digestive systems continue through the recto-urogenital canal, which opens via the lateral gonopores and the temporarily closed anal system. Spermiogenesis mainly occurs in the testes, whereas further maturation of the late spermatids and early spermatozoa occurs in the vasa deferentia and seminal vesicles. A maturation gradient (from spermatocytes to spermatozoa) is found from the posterior peripheral part of the testes to the anterior periphery and then centrally. During spermiogenesis the round nucleus becomes more osmiophilic and condensation of chromatin occurs. Later the nucleus elongates until it becomes rod-shaped in the early spermatozoa. In the second spermatid stage, a large vesicle is formed by saccules developed from the Golgi complex. This vesicle develops further and consists of three different osmiophilic parts with some crystal-like structures inside and is on the outside almost entirely surrounded by thick striated filaments. In the mid-piece the flagellum has a typical 9 × 2 + 2 axoneme and the two mitochondria are fused into a single sheet surrounding the flagellum. In the early spermatozoon stage an acrosomal-like cap structure with an acrosome filament appears proximal to the protruded rod-shaped nucleus. This cap is not formed by the Golgi complex and therefore might not be a true acrosome. Comparing the early spermatozoa of A. elegans with other cycloneuralians has shown some similarities with especially Kinorhyncha and Priapulida. These similarities are thought to be plesiomorphic.     

Ultrastructure of the Spermatozoon of an Opisthobranch, Tornatina sp. (Mollusca, Gastropoda, Retusidae)

The spermatozoon of Tornatina sp. has been studied with phase-contrast light microscopy and transmission electron microscopy. The head of the spermatozoon consists of an elongate acrosome which caps the apex of an unusually complex, helical nucleus. This elaborate nuclear morphology has not been previously reported, but possibly is found in other opisthobranch gastropod spermatozoa. An axoneme is inserted deeply into the base of the nucleus whilst posterior from the nucleus, the axoneme is ensheathed successively by the mitochondrial derivative (midpiece) and 'glycogen' granules (glycogen piece). The midpiece exhibits fine structure similar to that observed in other euthyneuran spermatozoa (paracrystalline and matrix materials) and possesses a single helical compartment filled with what are probably glycogen granules. A dense ring structure occurs at the junction of the midpiece and glycogen piece. The spermatozoon of Tornatina and other gastropods (prosobranch and euthyneuran) are compared.     

Structure of the Testes,Spermatozoa and Spermatozeugmata of Mimagoniates barberiRegan, 1907 (Teleostei: Characidae), an Internally Fertilizing,Oviparous Fish

Abstract The testis of Mimagoniates barberiis bipartite. Spermatogenic tissue is restricted to the anterior part. The posterior part of the testis is devoid of spermatogenic tissue and contains numerous efferent ducts filled with mature sperm. Cells in germinal cysts develop synchronously, sperm nuclei and flagella become oriented parallel in the late stages of spermiogenesis. In the caudal portion of the aspermatogenic part all sperms are arranged into unencapsulated sperm bundles — spermatozeugmata. Two types of spermatozeugmata are found both in the caudal portion of the testis and in milt. In the larger, spindle–shaped type, sperm flagella form the spindle tips. In the smaller ones, which have approximately a length of spermatozoon, the sperm are parallel and approximately in register. In both types sperm heads are arranged parallel. A mature spermatozoon is flail–shaped. The sperm head is highly elongated and situated alongside the flagellum, the tip of the head is directed backwards. Large mitochondria are situated on one side of the elongated nucleus only and form the tip of the head. Live spermatozoa move with the centriolar part ahead. Both testis and spermatozoon structure as well as formation of spermatozeugmata in M. barberiare highly derived features which perhaps evolved as adaptations to internal fertilization.     

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。     

Identification of agrinSN isoform and muscle-specific receptor tyrosine kinase (MuSK) [corrected] in sperm

We previously demonstrated several nicotinic acetylcholine receptor (nAChR) subunits and associated proteins in human sperm. Here, we identified in sperm for the first time two additional nAChR-associated molecules: (1) agrin(SN)Z(+) in human sperm localized in the posterior post-acrosomal, neck, and flagellar mid-piece regions; (2) a low-molecular weight isoform of muscle-specific receptor tyrosine kinase in human and mouse sperm localized in the flagellar mid-piece of human sperm.     

Spermiogenesis in the horseshoe crab,Limulus polyphemus

Groups of spermatids of Limulus polyphemus undergo differentiation in thin-walled cysts within the seminiferous tubules. The nucleus compacts to a spherical shape, but retains a much less condensed nuclear appendage, whose unique pores are each surrounded by a microtubule. The appendage, unmodified mitochondria, glycogen, and coated vesicles, all present in the mature spermatozoon, suggest an unusual degree of metabolic self-sufficiency of the cell. The acrosome is associated with a 50 μ-long acrosomal filament that penetrates the nucleus during spermiogenesis and coils up in the cytoplasm, enveloped by two outer nuclear membranes. The filament, which eventually comes to lie in the circumnuclear cisterna, retains a covering of one membrane during its discharge at the time of the acrosome reaction. The posterior region of the head forms a thin-walled collar with peculiar internal supports around the base of the flagellum. Serverance of intercellular bridges between spermatids, cytoplasm elimination, and rupture of the cyst precede liberation of the immature spermatozoa into the lumen of the seminiferous tubules. Notwithstanding its peculiarities, the Limulus spermatozoon, with its simple shape closely resembling that of annelids and molluscs, represents the most primitive arthropod spermatozoon congruent with the evolutionary stability of the xiphosurans.