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  • 1
    Electronic Resource
    Electronic Resource
    Ultrastructural observations on the gills of polychaetes (1978)
    Springer
    Helgoland marine research 31 (1978), S. 169-179 
    Details
    ISSN: 1438-3888
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The gills of several polychaete species belonging to 9 families were studied by scanning and transmission electron microscopy. The surface epithelium is covered by a thin cuticle which is invaded by microvilli penetrating the epicuticle in certain species. Some epithelial cells bear cilia, others are mucus-producing cells. The ciliary cells may be arranged in rows and maintain a constant flow of water over the gills. The distance between external water and blood stream differs considerably according to the species investigated. InMalacoceros the gills are characterized by closed afferent and efferent subepithelial vessels, which correspond to tubular invaginations of the coelomic wall. These vessels are lined by the basement lamina of the coelothelial cells, which are of the epitheliomuscular type. The vessels are open in the gills of other polychaetes and release the blood stream into a system of spaces immediately below the epidermis (e.g. in the branchial lamellae ofPectinaria andTerebellides). In several species the blood comes into very intimate contact with the cuticle (e.g. in the gill filaments ofDendronereides), but also in these animals both are separated by a very small epidermal layer.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02296995
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  • 2
    Electronic Resource
    Electronic Resource
    Detection and Induction of Cytochrome P450IA (CYP 1A)-Like Proteins in Julus scandinavius (Diplopoda) and Oniscus asellus (Isopoda): A First Analysis (1997)
    Springer
    Bulletin of environmental contamination and toxicology 58 (1997), S. 511 -517 
    Details
    ISSN: 1432-0800
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001289900364
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  • 3
    Electronic Resource
    Electronic Resource
    Fine structure of the genital system in the bee parasite,Varroa jacobsoni (Gamasida: Dermanyssina) with remarks on spermiogenesis, spermatozoa and capacitation (1986)
    Springer
    Experimental and applied acarology 2 (1986), S. 63-104 
    Details
    ISSN: 1572-9702
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The female genital tract ofVarroa jacobsoni is composed of a sperm-access system comprising paired solenostomes located between coxa III and IV, paired tubules, paired rami, an unpaired sperm duct, and an unpaired spermatheca. Another part of the female genital system is confined to egg development and oviposition. It is composed of an ovary (s.str.), in which oocytes mature, and a lyrate organ functioning as a nutrimentary structure. Both compartments, regarded as parts of the gonad, are connected by a region named the camera spermatis. This part is also in continuity with the oviduct I, which is provided with a muscular layer and numerous nerve endings. The following cuticle-lined oviduct II leads to the genital orifice through which the eggs are deposited. The fine structure of all these parts is described. Attention is drawn especially to the peculiar spermatheca which contains the “inner cells” which are thought to connect by way of free cells with a specialized region of the camera spermatis, thus establishing a “cellular bridge” through which penetration of capacitated spermatozoa into the ovary s.str. may occur. Lyrate organ and oocytes are connected via intercellular bridges/nutritive cords and are thus comparable to the telotrophic ovarioles of certain insects. The male genital system, composed of unpaired testis, paired vasa deferentia, unpaired accessory gland and ductus ejaculatorius, is described ultrastructurally. Spermiogenesis occurs in cysts and spermatozoa belong to the “ribbon type”. The vasa deferentia are provided with a muscular layer. For the first time receptors are detected in the proximal part or the ductus ejaculatorius. The accessory gland produces a proteinaceous secretion. Spermatozoa were observed in the female rami and spermatheca. Only in the latter were elongated, capacitated spermatozoa seen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01193355
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  • 4
    Electronic Resource
    Electronic Resource
    Light- and electron microscopical studies on the anatomy and function of the gills of krill (Euphausiacea, Crustacea) (1983)
    Springer
    Polar biology 1 (1983), S. 233-242 
    Details
    ISSN: 1432-2056
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The gills of the euphausiid crustaceans — Euphausia superba Dana, Meganycliphanes norvegica (Sars) — contain two longitudinal channels separated by epithelial tissue. These channels, functioning as afferent and efferent vessels, are connected at regular intervals by transverse channels in the gill filaments. By contraction of the gill muscles the krill is able to draw back its gills against its body wall, thus reducing water-current resistance. By increasing the haemolymphic pressure, the gill filaments can perhaps be unfolded again. Besides the muscle cells and supplying nerves, fine-structural observations revealed several cell types in the euphausiid gills, considered from their morphological characteristics to be transport cells, respiratory cells, secretory cells serving a transepithelial ion transport, gas exchange and secretion. A further cell type (flat cells) presumably has a regulatory and/or filtering function on the haemolymphic current. The components are arranged in a complex order, reflecting the functional efficiency of the organs concerned. Similarities are pointed out with dendrobranchia of Penaeus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00443194
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  • 5
    Electronic Resource
    Electronic Resource
    Fine structure of developing and mature spermatozoa in Tubiluchus (priapulida, tubiluchidae) (1983)
    Springer
    Zoomorphology 103 (1983), S. 219-227 
    Details
    ISSN: 1432-234X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Spermiogenesis and sperm cells of the meiobenthic priapulid Tubiluchus were described by means of the transmission electron microscope. The sperm cells are completely different from the male gametes of Priapulus, being elongated and thus indicating a different mode of sperm transfer. The anterior portion of the sperm head is characterised by a corkscrew configuration of nucleus and acrosome, both components being wrapped around each other. This kind of sperm cell has never been reported in other animal phyla.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00310479
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  • 6
    Electronic Resource
    Electronic Resource
    Mineral congregations, “spherites” in the midgut gland ofCoelotes terrestris (Araneae): Structure, composition and function (1988)
    Springer
    Protoplasma 143 (1988), S. 43-50 
    Details
    ISSN: 1615-6102
    Keywords: Coelotes terrestris ; Midgut gland ; Spherites ; Histochemistry ; Calcium phosphate ; Detoxification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Spherites in the digestive and secretory cells of the midgut gland of the agelenid spiderCoelotes terrestris were studied by electron microscopy and histochemical methods. Spherites measured 1–6 μm in diameter and were characterized by alternating layers of electron dense and electron lucent material. The main-components of spherites were calcium phosphates and calcium carbonates. Guanine and barium, as well as aminopeptidase and alkaline phosphatase were also present. The matrix consisted of proteins and carbohydrates. Numerous spherites were found together with excretory products within the excretory vacuoles of the digestive cells. Spiders fed with food containing lead, showed deposition of the metall in the spherites. It is then proposed that spherites, aside from their role in storing calcium and other ions, may function in detoxification of heavy metals.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01282958
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  • 7
    Electronic Resource
    Electronic Resource
    Fine structure of a secondarily developed eye in the freshwater moss-mite,Hydrozetes lemnae (Coggi, 1899) (Acari: Oribatida) (1988)
    Springer
    Protoplasma 146 (1988), S. 106-117 
    Details
    ISSN: 1615-6102
    Keywords: Chiasma opticum ; Hydrozetes ; Lamellated body ; Oribatida ; Photoneuron ; Secondary eye
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The lenticulus ofHydrozetes lemnae represents an eye composed of a single cuticular cornea underlain by flat extensions of epidermal cells, two pigment cells, and a pair of lamellated bodies. The latter consist of about 100 vertically arranged lamellae which are orientated longitudinally in the animal. The lamellated bodies are accompanied by glia cells. Two large fat body cells separate the paired components medially. Each lamellated body is connected to a perikaryon located in the brain. It is evident that these components are parts of photoneurons of the central nervous system. Their vertically directed extensions are dendritic branches, terminating under the cornea as lamellated bodies. It is assumed that these are the photosensitive parts of the two photoneurons which serve as receptor cells. The axon of each cell runs transversely through the brain and terminates in a small distinct optic neuropile close to the opposite perikaryon. Thus the resulting chiasma opticum comprises two axons only. The extraordinary composition of this eye corroborates the assumption that it is a secondary light sense organ.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01405919
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  • 8
    Electronic Resource
    Electronic Resource
    Internal fertilization in a meiobenthic priapulid worm:Tubiluchus philippinensis (Tubiluchidae, Priapulidia) (1988)
    Springer
    Protoplasma 143 (1988), S. 193-196 
    Details
    ISSN: 1615-6102
    Keywords: Derived spermatozoa ; Internal fertilization ; Tubiluchus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Internal fertilization is demonstrated in the priapulid wormTubiluchus philippinensis by the electron microscopic observation of sperm in the urogenital duct of female animals. This finding is of interest in that all other members of this group thus far examined have exhibited external fertilization.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01291164
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  • 9
    Electronic Resource
    Electronic Resource
    The fine structure of the lateral eyes ofNeocarus texanus Chamberlin and Mulaik, 1942 (Opilioacarida, Acari, Arachnida, Chelicerata) (1991)
    Springer
    Protoplasma 163 (1991), S. 19-33 
    Details
    ISSN: 1615-6102
    Keywords: Acari ; Arhabdomeric cells ; Crystalline tapetum ; Inverse eyes ; Neocarus texanus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Neocarus texanus, a “primitive” mite, bears two pairs of eyes, which are principally similar in ultrastructure. Each eye is covered externally by a cuticular cornea. It is underlain by flat sheath cells which send extensive processes into the retina. The retina is composed of distal and proximal cells. The 20 distal cells of the anterior eye are inversely orientated and form 10 disc-like rhabdoms. They represent typical retinula cells. Each rhabdom encloses the dendritic process of a neuron, the perikaryon of which is located outside the retina (proximal cells). The significance of this cell is not known. The retina is underlain by a crystalline tapetum. In the posterior eye 14 retinula cells form 7 rhabdoms in an arrangement similar to the anterior eye. The eyes of one side of the body are located within a capsule of pigment cells. Together the axons of the distal and proximal cells form the two optic nerves, one on each side of the body. The optic nerves leave the eyes anteriorly and terminate in two optic neuropils located in the brain. From structural evidence it is concluded, that the resolution of the eyes must be rather low. The peculiar proximal cells have not been observed previously in Acari. They probably resemble at best the eccentric cells and arhabdomeric cells of xiphosurans, scorpions, whip-scorpions and opilionids. Also, inverse retinae and tapeta of the present type have not been found in Acari until now, but are present in other Arachnida. Thus the eyes ofNeocarus texanus evidently represent a unique type within the Acari.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01323403
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  • 10
    Electronic Resource
    Electronic Resource
    Fine structure of spermatozoa and spermatogenesis ofSchizomus palaciosi, Reddell and Cokendolpher, 1986 (Arachnida: Uropygi, Schizomida) (1987)
    Springer
    Protoplasma 137 (1987), S. 1-14 
    Details
    ISSN: 1615-6102
    Keywords: Arachnida ; Acrosome ; Coiling ; Filaments ; Schizomus ; Spermatogenesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Spermatogenesis ofSchizomus palaciosi occurs in cysts in paired tubular testes located ventrally in the opisthosoma. Only few germ cells comprise one cyst. In early spermiogenesis an acrosomal complex composed of a spherical vacuole and a short acrosomal filament is established opposite of which a 9×2+3 flagellum emerges from a flagellar tunnel. The latter, however, is only a short-lasting structure. A manchette of microtubules surrounds nucleus and part of the acrosomal vacuole. The alterations in the arrangement of the microtubules during spermiogenesis are described. The spermatid finally is an elongate cell with a slender acrosomal vacuole on top of the helical nucleus. A deep implantation fossa filled with dense material is encountered. The acrosomal vacuole is accompanied by an intricate paracrosomal lattice structure not known at present of otherArachnida. This structure disappears during final spermiogenesis. The acrosomal filament (perforatorium) reveals filamentous subunits arranged in a regular pattern. Large ovoid mitochondria do not establish a distinct middle piece. Finally the elongate spermatid is coiled to form the mature spherical spermatozoon. The results are discussed under functional and taxonomical aspects.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01281172
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