La spermiogenèse d'Albula vulpes (L. 1758) (Poisson Albulidae)

Résumé La jeune spermatide possède un noyau arrondi, un diplosome proche de la membrane cellulaire auquel sont associées des formations paracentriolaires; une mitochondrie unique est disposée entre le diplosome et le noyau.Au cours de l'évolution de la spermatide, le noyau s'allonge latéralement, son grand axe étant perpendiculaire à l'axe flagellaire; la mitochondrie migre à l'extrémité latérale du noyau; le centriole distal donne un flagelle de type 9+0; le centriole proximal se prolonge le long du noyau puis sort de la cellule sous la forme d'un pseudo-flagelle. Le prolongement centriolaire est constitué de triplets classiques et de doublets d'un type particulier que nous avons appelés «doublets A–C».Les auteurs signalent la similitude des spermatozoïdes de cet Elopiforme avec les spermatozoïdes d'Anguilliformes ce qui serait en faveur de la proposition de Greenwood et al. de rassembler ces téléostéens dans le super-ordre des Elopomorphes.

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The spermiogenesis of Albula vulpes (L. 1758) (albulidae fish)

Summary The early spermatid possesses a round nucleus and a diplosome which is close to the cellular membrane and with which paracentriolar formations are associated; a sole mitochondrion is located between the diplosome and the nucleus.During the spermatid evolution, the nucleus is laterally elongated, its main axis being perpendicular to the flagellar axis; the mitochondrion migrates towards the lateral end of the nucleus; the distal centriole is extended along the nucleus, then leaves the cell as a pseudoflagellum. This centriolar extension is made up of regular triplets and of a particular type of doublets that we have called A–C doublets.The authors call attention to the similarity between the spermatozoa of this Elopiforme and the spermatozoa of the Anguilliformes. This observation favours Greenwood et al.'s proposition, to place these teleost into the super-order of Elopomorpha.

Les auteurs tiennent à remercier Mr. C. Chauve et Mr. J.-N. Roy pour leur collaboration.     

Changes in endoplasmic reticulum during spermiogenesis in the mouse

Summary Changes in the endoplasmic reticulum of mouse spermatids during spermiogenesis were examined by scanning electron microscopy, applying the OsO₄-DMSO-OsO₄ method, which permits 3-dimensional observation of cell organelles. At the same time, the endoplasmic reticulum was stained selectively by the Ur-Pb-Cu method, and 0.5 m-thick sections were prepared for observation by transmission electron microscopy. The results demonstrated stereoscopically the mode of disappearance of the endoplasmic reticulum. In spermatids of the early maturation phase, the endoplasmic reticulum was of uniform diameter, branched and anastomosed, forming a complicated three-dimensional network throughout the cytoplasm. A two-dimensional net was also noted to have formed just beneath the plasma membrane and about Sertoli cell processes invaginating the spermatid cytoplasm. As spermiogenesis progressed, the spread-out endoplasmic reticulum gradually aggregated to form a condensed, glomerulus-like structure consisting of a very thin endoplasmic reticulum connected to the surrounding endoplasmic reticulum. This structure corresponds to the so-called radial body. Thus, the endoplasmic reticulum may aggregate, condense, be transformed into a radial body, and be removed from the cytoplasm. The two-dimensional endoplasmic reticulum-net, just beneath the plasma membrane and surrounding processes of Sertoli cells, disappeared in spaces where the three-dimensional endoplasmic reticulum network was scarce. Both the two-dimensional endoplasmic reticulum-net structure and the three-dimensional endoplasmic reticulum network disappeared at the same time, indicating that they may be closely related.     

Male reproductive seasonality of the Snake-eyed Lizard,Ophisops elegans Ménétriés, 1832, from Lebanon (Reptilia: Lacertidae)

We studied the male reproductive cycle in a population of Ophisops elegans from Mount Sannine, Lebanon, by histological analysis. Testicular histology showed active spermatogenesis in spring, followed by a testicular regression at the end of summer and a subsequent recrudescence in autumn. Monthly variations in the epididymis, the ductus deferens and the sexual segment of the kidney were in synchrony with the testicular cycle. They were hypertrophied as spermatogenetic activity increased and atrophied as spermatogenetic activity decreased. Males of O. elegans showed a vernal type of spermatogenesis with a close relationship between the evolution of the seminiferous tubules and the secondary sexual characters.     

Parasperm: morphological and functional studies on nonfertile sperm

Sperm polymorphism, a phenomenon in which more than one type of sperm is produced within a species, occurs widely in animals from invertebrates to vertebrates. Sperm in this phenomenon can be categorized into fertile sperm and nonfertile sperm on the basis of fertilization ability. Nonfertile sperm can be further classified into parasperm and aberrant deformed sperm. Parasperm are sperm produced through a constant developmental process along with normal fertile eusperm, and they are readily distinguished from deformed sperm, which are irregularly crippled by unpredictable errors at certain stages during spermatogenesis. Sperm identified as parasperm occur widely in invertebrates but are presently quite limited in vertebrates. This may be the result of the deficiency both of studies on parasperm and of clear criteria to identify parasperm in vertebrates. Some vertebrates show unique spermatogenesis, such as symplastic spermatid and semicystic spermatogenesis. Thus, parasperm must be identified by comparing cells in each cyst and in semen, because irregularly shaped cells in the seminal duct could be either parasperm or normal spermatids. Although parasperm are identified by clear criteria in vertebrates, only in cottoid fishes to date, it is possible for parasperm to be discovered in other vertebrates. Recently, roles related to sperm competition have been reported in several species (e.g., the marine cottoid fish Hemilepidotus gilberti), and, with some of them, parasperm production is influenced by an intraspecific factor such as a sex ratio or the density of a population. Sperm competition is one of the important candidates for influencing evolution of parasperm functions, but not all parasperm seem to have a relation to sperm competition. Parasperm function may relate to the ecological conditions of each species that produces parasperm. Studies on parasperm function will be advanced by an ecological approach concerning male fertilization success as well as cytological investigation for parasperm. An erratum to this article is available at .     

Unusual cell organelles during spermiogenesis in two species of gobies (Gobiidae,Teleostei)

Summary Testes of Lesuerigobius friesii and Gobius bucchichi were studied in adult reproductive fish. During the onset of spermatid development, a peculiar system of alternating rough (RER) and smooth (SER) endoplasmic reticular tubules form rings distally to the cell nucleus. The RER tubules are seen to possess up to 12 ribosomes in cross-section, whereas the SER are strongly electron-dense. Nanotubules connect these stacks of tubules to the developing head and tail of the sperm. With ripening of the sperm these tubules disintegrate within the excessive cytoplasm. It seems likely that these are special forms of Macro-Golgi System that possibly provide protamines for the developing sperm.     

The E2 Ubiquitin-conjugating Enzyme UBE2J1 Is Required for Spermiogenesis in Mice

ER-resident proteins destined for degradation are dislocated into the cytosol by components of the ER quality control machinery for proteasomal degradation. Dislocation substrates are ubiquitylated in the cytosol by E2 ubiquitin-conjugating/E3 ligase complexes. UBE2J1 is one of the well-characterized E2 enzymes that participate in this process. However, the physiological function of Ube2j1 is poorly defined. We find that Ube2j1^−/− mice have reduced viability and fail to thrive early after birth. Male Ube2j1^−/− mice are sterile due to a defect in late spermatogenesis. Ultrastructural analysis shows that removal of the cytoplasm is incomplete in Ube2j1^−/− elongating spermatids, compromising the release of mature elongate spermatids into the lumen of the seminiferous tubule. Our findings identify an essential function for the ubiquitin-proteasome-system in spermiogenesis and define a novel, non-redundant physiological function for the dislocation step of ER quality control.     

The spermatogenesis and the sperm structure of Terebrantia (Thysanoptera, Insecta)

Spermatogenesis and the sperm structure of the terebrantian Aeolothrips intermedius Bagnall are described. Spermatogenesis consists of two mitotic divisions; the second is characterized by the loss of half of the spermatids, which have pyknotic nuclei. Early spermatids have two centrioles, but when spermiogenesis starts, a third centriole is produced. The three basal bodies give rise to three flagella; later these fuse into a single flagellum which contains three 9 + 0 axonemes. The basal bodies are surrounded by a large amount of centriole adjunct material. During spermiogenesis this material contributes to the shifting of the three axonemes towards the anterior sperm region parallel to the elongating nucleus, and it is transformed into a dense cylinder. In the mature spermatids the three axonemes amalgamate to create a bundle of 27 doublet microtubules. Near the end of spermiogenesis the dense cylinder of the centriole adjunct lies parallel to the nucleus and the axonemes. It ends where the mitochondrion appears at half-sperm length. We confirm that Terebrantia testes have a single sperm cyst; their sperm are characterized by a cylindrical nucleus, three axonemes fused into one, a small mitochondrion and a short cylindrical centriole adjunct which corresponds to the dense body described in a previous work. The acrosome is lacking. At the midpoint of the anterior half of the sperm the outline of the cross-section is bilobed, with the nucleus contained in a pocket evagination of the plasma membrane. These characters are discussed in light of a comparison between Tubulifera and Terebrantia.     

小鼠生精周期判定方法的改进

目的探讨一种可以在普通HE染色或苏木精复染标本上对精子发生周期进行简单划分的方法。方法应用PAS染色法与普通HE染色法相对照,对比观察小鼠睾丸各级生精上皮在精子发生不同时期的形态学变化特点。结果参照Clermont及Russel等制定的生精上皮时相的判定标准,把小鼠生精上皮分为XⅡ个期。结论通过对比总结,可以在普通HE染色或苏木精复染标本上对精子发生周期进行简单划分,并进一步辨别各型生精细胞。     

A comparative study of sperm morphology, cytology and activation in Caenorhabditis elegans, Caenorhabditis remanei and Caenorhabditis briggsae

Studies of sterile mutants in Caenorhabditis elegans have uncovered new insights into fundamental aspects of gamete cell biology, development, and function at fertilization. The genome sequences of C. elegans, Caenorhabditis briggsae and Caenorhabditis remanei allow for informative comparative studies among these three species. Towards that end, we have examined wild-type sperm morphology and activation (spermiogenesis) in each. Light and electron microscopy studies reveal that general sperm morphology, organization, and ultrastructure are similar in all three species, and activation techniques developed for C. elegans were found to work well in both C. briggsae and C. remanei. Despite important differences in the reproductive mode between C. remanei and the other two species, most genes required for spermiogenesis are conserved in all three. Finally, we have also examined the subcellular distribution of sperm epitopes in C. briggsae and C. remanei that cross-react with anti-sera directed against C. elegans sperm proteins. The baseline data in this study will prove useful for the future analysis and interpretation of sperm gene function across nematode species.     

Formation and rearrangement of spermatodesms in males of some Orthoptera Tettigoniidae

In the male genital tract of Tettigoniidae, the spermatodesms are composed of a limited number of spermatozoa whose nuclei and acrosomes are covered by a mucous cap. The formation of the cap begins in the testicular cyst during the lengthening of the apical prolongations of the spermatids and the spermatids’ simultaneous division into small bundles or spermatodesms. The cap material is formed from a loosely arranged material in the lumen of the cyst, probably produced by the secretory activity of the delimiting cells. Another characteristic aspect of the Tettigoniidae is the rearrangement of the cap inside the spermiduct that seems to start when material from the lumen of the organ enters from the basal part of the cap. Except for the fibrils of the peripheral lamina, the fibrils of the cap undergo a marked degradation process. The final organization of the spermatodesm cap is reached inside the seminal vesicles; it consists of the fibrillar peripheral lamina delimiting an interior made up of loosely arranged fibrils immersed in a finely granular matrix.