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  • 1
    Electronic Resource
    Electronic Resource
    Marsupial fertilization: Some further ultrastructural observations on the dasyurid Sminthopsis Crassicaudata (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 32 (1992), S. 277-292 
    Details
    ISSN: 1040-452X
    Keywords: Oocyte maturation ; Sperm - egg interaction ; Sperm incorporation ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Various morphological aspects of in vivo egg maturation and sperm - egg interaction were investigated in the Australian marsupial Sminthopsis crassicaudata with the transmission and scanning electron microscopes. Cortical granules invariably occurred in primary oocytes, with the number increasing after resumption of the first meiotic division. They generally occurred close to the oolemma, including the region near the oocyte nucleus. After mating, spermatozoa with intact acrosomes, which had a homogeneous electron-dense matrix, were found on the outer zona surface, but loss of acrosomal contents had occurred by the time of zona penetration. Sperm incorporation into the egg took place at the metaphase II stage of meiosis, and, at this time, cortical granules disappeared from the egg cortex. Sperm heads with condensed chromatin in the egg cytoplasm had an electron-dense layer of subacrosomal material over part of the dorsal nuclear surface, but no membranes were present around these incorporated spermatozoa. Sperm chromatin decondensation resulted in an elevation of egg cytoplasm, and the cell membrane over this area lacked microvilli. The pronuclear envelope was not laid down until after chromatin decondensation had occurred. By this time the fertilized egg had reached the uterus, and a smooth, electron-dense, shell membrane had been deposited. These observations, together with our previous findings, indicate that some of the processes of sperm - egg interaction are similar to those in eutherian mammals, whereas others appear highly divergent.
    Additional Material: 47 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1080320314
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  • 2
    Electronic Resource
    Electronic Resource
    Unusual nuclear structure of the spermatozoon in a marsupial, Sminthopsis crassicaudata (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 37 (1994), S. 78-86 
    Details
    ISSN: 1040-452X
    Keywords: Marsupial ; Sperm head ; Chromatin ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The organization of sperm chromatin in the dasyurid marsupial, Sminthopsis crassicaudata, was investigated using various morphological techniques. Transmission electron microscopy indicates two quite distinct chromatin regions became evident late in spermiogenesis with an outer globular region containing blocks of very electron-dense chromatin. Fluorescent light microscopical studies after staining with DNA dyes and 7-amino actinomycin D of testicular, caput, and cauda epididymal spermatozoa showed that this region fluoresced less brightly than the rest of the nucleus, indicating the presence of fewer DNA binding sites. Freeze fracture showed that the chromatin in most of the nucleus had randomly arranged particles of various sizes, but that of the outer region was composed entirely of small particles. This outer region was more resistant to low concentrations of the ionic detergent, SDS, whereas both guanidine hydrochloride and urea together with sodium chloride generally dispersed all the chromatin except that in the outer globular region and in a localized area of the nucleus beneath the acrosome. This study has thus revealed that the outer globular chromatin of these spermatozoa responds differently to ionic detergents and protein denaturing agents and has a different chromatin organization than most of the rest of the nucleus. The significance of these differences remains, however, to be determined. © 1994 Wiley-Liss, Inc.
    Additional Material: 23 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1080370111
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  • 3
    Electronic Resource
    Electronic Resource
    Distribution of filamentous actin in and around spermatids and in spermatozoa of Australian conilurine rodents (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 30 (1991), S. 369-384 
    Details
    ISSN: 1040-452X
    Keywords: F-actin ; Sperm head ; Australian rodents ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The distribution of filamentous actin around the maturing sperm head and in spermatozoa of four species of Australian conilurine rodents was investigated at the light and electron microscopic levels. Similar results were obtained for all the species studied. Mechanically isolated spermatids had NBD-phallacidin-positive longitudinal bands of fluorescence over the dorsolateral surface and, in late spermatids, bands of bright fluorescence passed perpendicularly from the dorsal convex to ventral concave surface. TEM observations indicated that these regions corresponded to filaments of ectoplasmic specializations and granular filamentous material around the tubulobulbar complexes, respectively. In testicular and cauda spermatozoa NBD-phallacidin fluorescent material was present in the two ventral processes that extended from the upper concave surface of the sperm head; also fainter material occurred along the concave border and as a dorsocaudal spur. Its distribution was identical for testicular and cauda spermatozoa. TEM of late spermatids showed that in the ventral process closest to the apical hook there were between 170 and 245 filaments, which attached to the inner surface of the postacrosomal dense lamina; in the more caudal ventral process about 70 filaments occurred. No filaments were, however, visible in the mature spermatozoon but, after immunocytochemical labelling for actin, deposition of gold particles was evident over ventral processes of both late spermatids and cauda spermatozoa. Within the female tract these ventral processes made contact with the zona matrix and were taken into the egg cytoplasm unchanged in morphology. The possible functional significance of the filamentous actin in these structures is discussed.
    Additional Material: 39 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1080300412
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  • 4
    Electronic Resource
    Electronic Resource
    Morphological changes in the oocyte and its surrounding vestments during in vivo fertilization in the dasyurid marsupial sminthopsis crassicaudata (1990)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 204 (1990), S. 177-196 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: This light and transmission electron microscopical study shows that the first polar body is given off before ovulation and that part of its cell membrane and that of the surrounding oocyte have long microvilli at the time of its ejection. Several layers of cumulus cells initially surround the secondary oocyte and first polar body, but the ovulated oocytes in the oviducts in the process of being fertilized do not have cumulus cells around them. Partly expelled second polar bodies occur in the oviduct; they are elongated structures that lack organelles and have electron-dense nuclei. A small fertilization cone appears to form around the sperm tail at the time of sperm entry into the egg and an incorporation cone develops around the sperm head in the egg cytoplasm. In three fertilized eggs a small hole was seen in the zona, which was presumably formed by the spermatozoon during penetration. Cortical granules, present in ovarian oocytes, are not seen in fertilized tubal or uterine eggs; release of their contents probably reduces the chances of polyspermy, although at least one polyspermic fertilized egg was seen and several other fertilized eggs had spermatozoa within the zona pellucida. In the zygote the pronuclei come to lie close together, but there was no evidence of fusion. A “yolk mass,” which becomes eccentric before ovulation, is extruded by the time the two-cell embryos are formed, but many vacuoles remain in the non-yolky pole of the egg. A shell membrane of variable thickness is present around all uterine eggs but its origin remains undetermined.
    Additional Material: 51 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1052040207
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  • 5
    Electronic Resource
    Electronic Resource
    Novel photocycloadditions of electron-deficient nitrones to 2-methyl-2-butene (1991)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1991 (1991), S. 513-517 
    Details
    ISSN: 0170-2041
    Keywords: Nitrones, electron-deficient ; Oxaziridines ; Dipolarophiles ; [3+2]Photocycloadditions ; Oxazolidines ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In Order to decrease the ground state reactivity and increase their potential for [3+2] cycloadditions, cyano- and methoxy-carbonyl-substituted nitrones 1a and 1b, respectively, were prepared and irradiated in the presence of electron-rich alkenes such as 2 to afford the corresponding oxazolidines in which th oxygen atom becomes attached to the least substituted terminus of the olefin and nitrogen attaches to the more highly substituted counterpart. While the oxazolidines 12a and 12b obtained from 1b, via the intermediacy of oxaziridine(s) 15 and subsequent N—O bond scission, are isolated and characterized, the oxazolidin(s) 18 formed bny cyclization of 1a are more labile and may undergo ionization to the stabilized oxazolinium ion 19 followed by nucleophilic attack by cyanide ion with accompanying ring opening to afford 6. A sequential diradical mechanism is proposed to rationalize the formation of the observed photoproducts 5 and 6.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199119910194
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  • 6
    Electronic Resource
    Electronic Resource
    An analytical electron microscopic investigation of precipitation in an Al-Cu-Zn-Mg-Ag alloy (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Microscopy Research and Technique 24 (1993), S. 359-366 
    Details
    ISSN: 1059-910X
    Keywords: TEM ; Morphology ; Crystallography ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: The distribution, morphology, chemistry, and crystallography of the precipitates formed during aging of an Al-Cu-Zn-Mg-Ag alloy have been studied using analytical transmission electron microscopy. The first precipitates to appear during aging at 150°C were thin hexagonal-shaped plate-like precipitates which formed on the {111}Al planes. These precipitates had a face-centred orthorhombic crystal structure and their composition was essentially CuAl2 although they contained a trace of silver. At peak hardness the microstructure consisted of the plate-like precipitates on {111}Al planes and θ′ precipitates on {100}Al planes. Overaging resulted in the precipitation of equilibrium θ, CuAl2, which exhibited a lath morphology and an orientation-relationship with the matrix (210)Al ∥(110)γ; (001)Al misorlented from (001)γ by ∼6°. Prolonged overaging at 250°C resulted in the formation of cuboid-shaped Al5(Cu,Zn)6Mg2 precipitates which had a cubic crystal structure and a cube:cube orientation-relationship with the matrix. © 1993 Wiley-Liss, Inc.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jemt.1070240409
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  • 7
    Electronic Resource
    Electronic Resource
    Enhanced in vitro growth of murine fibroblast cells and preimplantation embryos cultured in medium supplemented with an amphipathic peptide (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 31 (1992), S. 106-113 
    Details
    ISSN: 1040-452X
    Keywords: Embryo development ; Lytic peptide ; Growth factor ; Cecropin ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Preliminary studies on the proliferative effects of lytic peptides were carried out using NIH 3T3 murine fibroblast cells and human lymphocytes. Cells were cultured in various concentrations of three different amphipathic peptides (SB-37, Shiva-1, and Vishnu), and enhanced proliferation was determined by uptake of 3Hthymidine with treated cells compared with control cultures. Enhanced proliferation of 3T3 cells was observed in cultures containing 50 μM or less SB-37. The primary study consisted of 263 four-cell- to eight-cell-stage mouse embryos from naturally bred mice and incubated in Whitten's medium containing 0.2, 1, or 10 μM of the amino terminus of an amphipathic cecropin B analog (Vishnu) or in Whitten's medium alone. Embryos were cultured to the hatched blastocyst stage, and effect of treatment was determined by the rate of growth to that stage of development. Statistical analysis revealed that culture in all three levels of Vishnu significantly accelerated in vitro growth of these stages of preimplantation embryos compared with controls. These results indicate that Vishnu promotes increased cleavage rates of embryos in vitro. A growth factor receptor clustering mechanism of action is proposed. This peptide may have some potential as an embryo culture medium additive to enhance in vitro growth rate.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1080310204
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  • 8
    Electronic Resource
    Electronic Resource
    Tetrazolverbindungen. 6. Acylierung von 1-Aryl-5-(2-dialkylamino-vinyl)-1 H-tetrazolen mittels Trifluor- und Trichloracetanhydrid (1993)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 335 (1993), S. 461-464 
    Details
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Tetrazole Compounds. 6. Acylation of 1-Aryl-5-(2-dialkylamino-vinyl)-1 H-tetrazoles by Trifluoro- and Trichloroacetic Anhydrides
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19933350513
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  • 9
    Electronic Resource
    Electronic Resource
    Tetrazolverbindungen. 7. Neuartig verknüpfte Pyrazolyl- und Isoxazolyl-tetrazole aus Enaminoketon-Vorstufen (1994)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 336 (1994), S. 79-82 
    Details
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Tetrazole Compounds. 7. New Types of Pyrazolyl- and Isoxazolyl-tetrazoles from Enamino Ketone Precursors
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19943360118
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  • 10
    Electronic Resource
    Electronic Resource
    Ultrastructure of free neuromasts of Bathygobius fuscus (gobiidae) and canal neuromasts of Apogon cyanosoma (apogonidae) (1991)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 209 (1991), S. 111-120 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Light and electron microscopic observations were made on the lateral line organs of the free neuromasts of the goby Bathygobius fuscus and the canal neuromasts of the cardinal fish Apogon cyanosoma. As in other lateral line systems, each neuromast consists of hair cells, supporting cells and mantle supporting cells, the whole being covered by a cupula. In B. fuscus the free neuromasts are mounted on papillae and have hair cells with stereocilia up to 2.5 μm long and a single kinocilium at least 25 μm long. Each neuromast is covered by a vane-like cupula that can be divided into two regions. The central region over the sensory area contains columns of myelin-like figures. These figures are absent from the outer region covering the mantle. The canal neuromasts of A. cyanosoma are diamond-shaped with up to 1,500 hair cells. The cupula is unusual in having a channel that lies over the sensory region. The hair cells have up to 45 stereocilia, the tallest reaching 2.5 μm, and a kinocilium at least 5 μm long. Tip links are shown for the first time between rows of stereocilia of the hair cells of lateral line neuromasts. The presence of tip links has now been demonstrated for all acousticolateral hair cell systems.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1052090109
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