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  • Ultrastructure  (116)
  • Springer  (116)
  • American Chemical Society
  • Nature Publishing Group
  • 1980-1984  (116)
  • 1950-1954
  • 1935-1939
  • 1925-1929
  • 1984  (65)
  • 1982  (51)
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  • Springer  (116)
  • American Chemical Society
  • Nature Publishing Group
  • Wiley-Blackwell  (1)
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  • 1980-1984  (116)
  • 1950-1954
  • 1935-1939
  • 1925-1929
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  • 1
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    Springer
    Calcified tissue international 34 (1982), S. 273-279 
    ISSN: 1432-0827
    Keywords: Odontogenesis ; Ultrastructure ; Alkaline phosphatase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The ultrastructural localization and gradient of activity of alkaline phosphatase were studied with respect to cell differentiation, matrix synthesis, and matrix mineralization in the incisor and molar teeth of 4-day-old Sprague-Dawley rats. The animals were perfused intracardially at room temperature with 2.5% glutaraldehyde in 0.1M sodium cacodylate (pH 7.4) with 3–4% sucrose. The jaws were dissected, immersion-fixed for 24 h, and the incisor and molar tooth germs removed. These were demineralized in 10% EDTA in NaOH (pH 7.4) with 7% sucrose. After reactivation of the enzyme with 0.1M MgCl in Tris-maleate buffer (pH 7.4) at 4°C, the teeth were incubated for alkaline phosphatase in a medium consisting of 6 ml 3% sodiumβ-glycerophosphate, 4 ml 0.2M Tris-HCl buffer (pH 9.2), 3 ml 1.6% MgSO4, 12 ml 0.5% lead citrate (pH⋍12), and 2.1 g sucrose. The pH was adjusted to 9.2 with 0.2M HCl, the volume made up to 30 ml, and the solution centrifuged for 10 min at 5000 rpm. Control teeth were incubated in medium minus the substrate. Finally, the specimens were routinely post-fixed and embedded for sectioning and examination with a Philips 300 electron microscope. A gradient of alkaline phosphatase activity was mapped along the developing teeth in the cells of the stratum intermedium, the proximal borders of the ameloblasts, the early dentine matrix, the predentine-dentine border, matrix vesicles, and the plasma membranes of odontoblasts and subodontoblast cells. The gradient of alkaline phosphatase activity was evident in the forming tooth from the cervical loop to the crown apex and was related to the cellular events, matrix synthesis, and matrix mineralization occurring during odontogenesis.
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  • 2
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    Calcified tissue international 36 (1984), S. 550-555 
    ISSN: 1432-0827
    Keywords: Enamel crystals ; Length ; Shape ; Apatite ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary An original method for fractionating and preparing isolated crystals of homogeneous size was developed. It was demonstrated that enamel apatite crystals are at least 100 µm long. The flexibility of the very long crystallites was demonstrated. Crystal curvatures, accounting for the irregular course of the prisms through the enamel thickness, were visualized and measured. It was shown that in the deep forming enamel layer, lateral branches may grow out of the crystals and crystal fusing often occurs, inducing the crystallites to assume pyramidal shapes with their wide bases pointing toward the dentino-enamel junction and one or two tops toward Tomes' processes. During the maturation process, the two tops of the still immature crystals also fuse so that the mature crystals acquire a rodlike aspect, with parallel faces and steplike graduations along thec axis, allowing a close contact between the crystals. These results support the hypothesis that the crystallites would be continuous from the dentino-enamel junction to the surface.
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  • 3
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    Calcified tissue international 34 (1982), S. 382-390 
    ISSN: 1432-0827
    Keywords: Avian osteopetrosis ; Avian oncornavirus ; Ultrastructure ; Calcification ; Bone cells
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Diaphyseal tibial bone of 12.5 – 13-day and 19-day-old embryos and 20-day-old hatched chicks infected with retrovirus MAV.2-O were examined by transmission electron microscopy. The viruses were associated with lining osteoblasts and osteocytes. Whereas the infection of the osteoblast layer seemed to be a transient stage, virus association with osteocytes was a constant and main ultrastructural feature. The viruses were found either in the osteoid or in the periosteocytic space of the bone lacunae. They arose from dense cytoplasmic areas located near the cell plasmalemma via a budding process. The newly budded virus particles often had a large tail or a fine stalk-like process lost in the extracellular space. The viruses underwent calcification by deposition of inorganic material and were incorporated in the bone trabeculae. No production of virus was observed in typical osteoclasts with well-differentiated ruffled borders. The viral-induced avian osteopetrosis seemed to result from increased bone deposition through stimulation of osteoblast and osteocyte activities, whereas osteoclastic bone resorption seemed to be undisturbed.
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  • 4
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    Archives of microbiology 133 (1982), S. 11-19 
    ISSN: 1432-072X
    Keywords: Cyanobacteria ; Ultrastructure ; Mastigocladus laminosus ; Fischerella ; True branching
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The morphology and ultrastructure of the thermophilic cyanobacteriumMastigocladus laminosus were examined by scanning and transmission electron microscopy. Mature cultures consisted of relatively old, wide filaments that branched frequently to form younger, thinner filaments. The cells of the younger filaments had a consistently cylindrical morphology, while those of older filaments were rounded and pleomorphic. The internal ultrastructure of the cells depended somewhat on their age. As young cells became larger and wider, their thylakoids underwent slight rearrangement and spread out toward the center of the cytoplasm. Polyphosphate bodies, carboxysomes (polyhedral bodies), and lipid-body-like structures increased in number as the cells aged, but ribosomes and cyanophycin granules were depleted. Cell division involved septum formation followed by ingrowth of the outer membrane and sheath. Cells in older filaments were separated from each other by a complete layer of sheath material. Septum formation in older cells was also seen to occur parallel to the long axis of the filament, thereby confirming that true branching took place.
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  • 5
    ISSN: 1432-072X
    Keywords: Methanogenium tatii ; Ultrastructure ; Physiology ; Glycoproteins ; DNA-DNA Homology ; Taxonomy ; Archaebacteria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A new coccoid methanogen, Methanogenium tatii, was isolated and characterized. The mesophilic isolate can grow on and produce methane from H2:CO2 and formate. For growth acetate is strictly required. The cell shape, the G+C content of 54 mol% and DNA-DNA homology data suggest it to be a Methanogenium species.
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  • 6
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    Archives of microbiology 138 (1984), S. 229-232 
    ISSN: 1432-072X
    Keywords: Actinomycetes ; Streptomyces torulosus ; Morphology ; Ultrastructure ; Verrucate spores ; Knobby ornamentation ; Sheath
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The type strain of Streptomyces torulosus Lyons and Pridham (1971) was studied by scanning- and transmission electron microscope. Spore chains were formed in spirals by aerial mycelium. The spores were connected by nozzles in which small channels could be observed. The knobby ornamentations of the spores arised on a thin fibrous sheath, enveloping the spore chains. These irregular blunt projections, called knobs, had varying diameters of 100 to 250 nm. The base of the knob, consisting of globose to flattened electron dense material, was sitting directly on the sheath. It was covered by several small vesicles of the same material. Each hollow vesicle beared a thin bowlshaped shell of electron transparent material. In general, the cupular bowls and their supporting vesicles became easily depressed on their base, but not detached from the surface of the spores. This type of knobby spore ornamentation was suggested to be designated as a verrucate spore type.
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  • 7
    ISSN: 1432-072X
    Keywords: Nitrobacter hamburgensis ; Nitrite oxidoreductase ; Nitrate reductase ; Molybdenum iron-sulfur protein ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Nitrite oxidoreductase, the essential enzyme complex of nitrite oxidizing membranes, was isolated from cells of the nitrifying bacterium Nitrobacter hamburgensis. The enzyme system was solubilized and purified in the presence of 0.25% sodium deoxycholate. Nitrite oxidoreductase oxidized nitrite to nitrate in the presence of ferricyanide. The pH optimum was 8.0, and the apparent K m value for nitrite amounted to 3.6 mM. With reduced methyl-and benzylviologen nitrite oxidoreductase exhibited nitrate reductase activity with an apparent K m value of 0.9 mM for nitrate. NADH was also a suitable electron donor for nitrate reduction. The pH optimum was 7.0. Treatment with SDS resulted in the dissociation into 3 subunits of 116,000, 65,000 and 32,000. The enzyme complex contained iron, molydbenum, sulfur and copper. A c-type cytochrome was present. Isolated nitrite oxidoreductase is a particle of 95±30 Å in diameter.
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  • 8
    ISSN: 1432-234X
    Keywords: Ultrastructure ; Gills ; Epithelial cells ; Polychaeta
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The ultrastructure of gill epidermal cells of Diopatra neapolitana and their relationship with blood spaces are described. The existence of a basal infolding complex, related to the blood spaces, is also reported. A possible involvement of these cells in osmoregulation and ion interchange, apart from their well-known role in respiration, is suggested.
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  • 9
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    Theoretical and applied genetics 68 (1984), S. 305-309 
    ISSN: 1432-2242
    Keywords: Impatiens ; Microspore mitosis ; Plastid distribution ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary This paper describes the unequal distribution of plastids in the developing microspores of Impatiens walleriana and Impatiens glandulifera which leads to the exclusion of plastids from the generative cell. During the development from young microspore to the onset of mitosis a change in the organization of the cytoplasm and distribution of organelles is gradually established. This includes the formation of vacuoles at the poles of the elongate-shaped microspores, the movement of the nucleus to a position near the microspore wall in the central part of the cell, and the accumulation of the plastids to a position near the wall at the opposite side of the cell. In Impatiens walleriana, the accumulated plastids are separated from each other by ER cisterns, and some mitochondria are also accumulated. In both Impatiens species, the portion of the microspore in which the generative cell will be formed is completely devoid of plastids at the time mitosis starts.
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  • 10
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    Cell & tissue research 235 (1984), S. 309-318 
    ISSN: 1432-0878
    Keywords: Ascidian ; Gut ; Cell involution ; Ultrastructure ; Phagocytes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Degenerative changes in the digestive tract of zooids of Botryllus schlosseri were studied by light and electron microscopy. Three main processes occurred in the tissues: contraction, involution and phagocytosis. The contraction of epidermis and peribranchial epithelium in which cytoplasmic microfilaments probably participate, seemed to have a special role in compressing the underlying organs. During contraction most of the body cavities collapsed, the branchial walls disintegrated and the fragments were rapidly taken up by large phagocytes. The gut epithelium retained its apparent continuity longer, though isolated phagocytes infiltrated it to eliminate single cells. Cell degeneration came about chiefly either through swelling and lysis of cells or through loss of water and condensation of cytoplasm and nucleus. The fate of all regressed tissues was to be engulfed and digested by wandering phagocytes. However, it was also observed that numerous cells of different epithelia could act as fixed phagocytes by engulfing cell debris and entire cells into heterophagic vacuoles.
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  • 11
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    Cell & tissue research 235 (1984), S. 347-356 
    ISSN: 1432-0878
    Keywords: Blastocyst ; Ultrastructure ; Pig
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Between days 8 and 11 of pregnancy spherical blastocysts from 0.3 to 10 mm in diameter were flushed from the uterine horns of Dutch Landrace pigs. A description of their ultrastructure is given, and the uptake of horseradish peroxidase and ferritin is demonstrated. The ultrastructure of the trophoblast was similar at all ages studied. The trophoblast which has many apical microvilli is able to take up and digest the macromolecules which were offered in the in vitro incubation medium. The hypoblast consists of flattened cells. In blastocysts 2 mm and larger, compact cells bearing microvilli are found below the embryoblast. Cell organelles indicating protein synthesis are found within hypoblast cells of such blastocysts. In the embryoblast, local concentrations of cell organelles are visible, indicating that differentiation has started. After the disappearance of Rauber's layer, which takes place when the blastocyst reaches a diameter of about 2 mm, superficial embryoblast cells develop short microvilli. The cells do not absorb ferritin or peroxidase but are dependent on the trophoblast for their food requirements. All cell layers in the blastocyst contain mitochondria that have characteristics of those found in steroidproducing cells. The significance of the uptake and digestion of macromolecules by trophoblast cells, the synthesis of protein by hypoblast cells and the possible synthesis of steroids is discussed with respect to the relationship between the cell layers of the blastocyst and in the context of conceptomaternal relationships.
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  • 12
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    Cell & tissue research 236 (1984), S. 365-372 
    ISSN: 1432-0878
    Keywords: Skeletal muscles ; Myofibrils ; Ultrastructure ; Exertion ; Man
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The fine structure of muscle fibres from m. vastus lateralis of nine healthy males (mean age 26 years) was investigated. Four individuals constituted non-exercised controls while five subjects participated in a two-months eccentric muscular training program. Specimens from the controls showed a well-preserved, regular myofibrillar band pattern while changes in the myofibrillar architecture were constantly found in specimens taken after the training program. These changes consisted of Z-band alterations, Z-bands being out of register, extra sarcomeres, Z-band extensions and bisected Z-bands. Between the separated Z-band halves, thin and thick myofilaments as well as abundant glycogen particles and/or ribosomes, were observed. Type-2 (fast-twitch) fibres were predominantly affected. Contrary to the controls the trained individuals constantly showed a greater variation in sarcomere lengths in Type-2 fibres than in Type-1 fibres. It is concluded that muscular work of high tension can induce fine-structural alterations. When repeated over a long period of time, extreme tension demands seem to initiate reorganization in the muscle fibres, predominantly in the, ultrastructurally defined, Type-2 fibres. This adaptation probably results in a better stretchability of the muscle fibres, reduces the risk for mechanical damage and brings about an optimal overlap between actin and myosin filaments.
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  • 13
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    Cell & tissue research 236 (1984), S. 393-397 
    ISSN: 1432-0878
    Keywords: Smooth muscle ; Salamander, Amphiuma ; Ultrastructure ; Stereology ; Volume: surface area ratio
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary An ultrastructural and stereological examination was performed on stomach smooth muscle of the salamander Amphiuma. This tissue has very large cells, ranging up to 12×1500 μm when relaxed. The extracellular space is 31% of the tissue volume, and the tissue contains 84.6% water. These values are similar to those of other amphibian and mammalian gastrointestinal smooth muscle. The cells possess the usual smooth muscle organelles. Thick, thin and intermediate filaments are present, along with membrane-associated and cytoplasmic dense regions. There is a well-developed sarcoplasmic reticulum and many microtubules. Caveolae are found in rows along the cellular surface; the caveolae increase the cellular surface area by about 70%. The ratio mean volume: surface area of the cells is 1.26 μm. This tissue appears to be typical of gastrointestinal smooth muscle, with the exception of the very large size of the cells.
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  • 14
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    Cell & tissue research 236 (1984), S. 619-628 
    ISSN: 1432-0878
    Keywords: Gastrotricha, freshwater ; Sperm, reduced ; Ultrastructure ; Spermatogenesis ; Temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Spermatogenesis and spermiogenesis in Lepidodermella squammata are confined to the postparthenogenic phase of the life cycle and coincide with developmental changes in the bilateral female gonads. Male stages are bilateral but asynchronous, in the lateral abdomen anterior to the female gonads. Maximum observed sperm production is two packets per side, or 64 sperm. Sperm formation occurs more rapidly at 27° C than at 20° C (p〈0.001), requiring as little as 1 day. Two spermatogonial mitotic divisions produce a clone of four primary spermatocytes connected by bridges (stage 1). Centrioles are absent. Development occurs within a cyst. Meiotic divisions produce 16 spermatids (stage 2), each containing a dense, elongate, tapered nucleus. Cytoplasmic membranes enclose one end of the nuclear rod, excluding all other organelles. Completion of this process results in stage 3, a packet of 16 sperm associated with one dense sphere, a modified ‘residual body’ containing cytoplasmic debris. The residual body then disappears, leaving the sperm packet of stage 4. Each mature sperm is a dense nuclear rod with surrounding membranes, lacking acrosome, mitochondrion, centrioles, and flagellum. Function of sperm has not been demonstrated. The spermatozoa are of a reduced type not previously described.
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  • 15
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    Cell & tissue research 236 (1984), S. 629-636 
    ISSN: 1432-0878
    Keywords: Oocytes, primary ; Gastrotricha, freshwater ; Ultrastructure ; Synaptonemal complex ; X-body
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Six small cells are present in each of the bilateral gonads of parthenogenically reproductive Lepidodermella squammata. Early in the extended postparthenogenic phase of the life history, these cells undergo limited proliferation followed by differentiation. Primary oocytes of three types are present 0.3 days after deposition of the final parthenogenic egg: small oocytes with presynaptic nuclei; intermediate oocytes with nuclei containing synaptonemal complexes; and larger oocytes with a germinal vesicle. Oocytes persist without further development at least until day four of the postparthenogenic phase. Older isolated animals may contain and even deposit an enlarged egg, but successful progeny does not result. Oocytes are located at the anterior pole of each of the bilateral gonads, adjacent to developing male tissues producing sperm. More posterior cells in the gonad are initially undifferentated in the postparthenogenic phase. Dorsal and central cells first show specialization for secretory activity, and by day four contain peripheral layers of RER and central accumulations of polymorphic secretion droplets. The posterior and ventral cells produce secretion droplets that aggregate into an enlarging bilobed structure called the X-body. Two or three cells in each gonad contribute secretions to the X-body, which is intracellular in a secondary syncytium formed by the contributing cells. Functions for the postparthenogenic gametes and for the X-body are not yet demonstrated.
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  • 16
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    Cell & tissue research 236 (1984), S. 693-697 
    ISSN: 1432-0878
    Keywords: Intermediate filaments ; Microtubules ; Caveolae ; Bullfrog ; Arachnoid mater ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In the bullfrog, the meninges surrounding the central nervous system include an arachnoid mater that contains layers of cells with abundant intermediate filaments (IFs) having unique organizational characteristics. This membrane contains an inner lamina of cells that resemble fibroblasts and an outer lamina of flattened cells that are almost filled with IFs. The IFs of the outer arachnoid are arranged in compact, arching bundles that lie parallel to the outer surface of the central nervous system. Thus, sections cut tangentially to the membrane reveal bending of filament bundles, whereas transverse sections do not. In some cells bordering the subdural space, bundles of filaments are organized into highly-ordered spiral arrays. Attachments to the numerous desmosomes and, apparently, to the nuclear envelope suggest anchoring of cytoplasmic structures by the IF system. Microtubules occur primarily near the plasma membrane and the nucleus. Numerous caveolae also are associated with the plasma membrane. The unusual abundance, organization, and cytoplasmic relations of IFs in the bullfrog arachnoid suggest that this membrane may serve as an important model for study of fundamental cytoskeletal relations and function.
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  • 17
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    Cell & tissue research 237 (1984), S. 277-284 
    ISSN: 1432-0878
    Keywords: Swimbladder ; Teleost ; Cholinergic nerves ; Adrenergic nerves ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The general structure, ultrastructure and innervation of the swimbladder of the smooth toadfish, Tetractenos glaber, were examined with light-microscopic, fluorescence-histochemical, and transmission electron-microscopic techniques. The structure of the swimbladder is similar to that of other euphysoclists. Fluorescence histochemistry showed adrenergic fibres in both the secretory and resorptive areas of the swimbladder. Transmission electron microscopy revealed two morphologically distinct axon profiles type-I profiles containing many small, flattened vesicles; type-II profiles containing both large, granular vesicles and rounded, small clear vesicles in varying proportions. The gas-gland cells and surrounding muscularis mucosae are innervated by both type-I and type-II fibres. Type-I fibres also innervate pre-rete arteries. The rete- and gas-gland capillaries do not appear to be innervated. Arteries running to the resorptive area are innervated by type-I fibres. Both type-I and type-II profiles make contact with the muscularis mucosae in the resorptive area. Only type-I fibres innervate the radial dilator muscle in the oval sphincter region, whereas only type II fibres innervate the circular muscle of the oval sphincter. Type-I fibres took up α-methyl-noradrenaline, and could not be found after pre-treatment with 6-hydroxydopamine. They are, therefore, assumed to be adrenergic. Type-II fibres were tentatively identified, by exclusion, as cholinergic.
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  • 18
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    Cell & tissue research 237 (1984), S. 537-547 
    ISSN: 1432-0878
    Keywords: Scale ; Regeneration ; Ultrastructure ; Cichlid ; Hemichromis bimaculatus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Scale regeneration has been studied in Hemichromis bimaculatus. The removed scale, which serves as a control, is covered by its surrounding scleroblasts as can be seen with scanning electron microscopy. Subsequently, during regeneration, a population of scleroblasts arises in the empty dermal pocket as shown with transmission electron microscopy. At first, an elongated papilla of regeneration forms, probably from the differentiation of dermal fibroblasts. A scale anlage composed of the osseous layer appears in the middle of the papilla, which becomes a regenerating bag. All the surrounding large scleroblasts are involved in scale formation, although later three populations of scleroblasts specialize according to their location around the scale. Superficial scleroblasts flatten when the final thickness of the osseous layer of the scale is attained; the deep scleroblasts are responsible for the formation of the basal plate whereas marginal scleroblasts increase the diameter of the osseous layer of the scale. During scale regeneration, scleroblasts are more numerous and larger than during scale ontogenesis. In particular, deep scleroblasts form a columnar epithelium when the basal plate is laid down, a feature which is not found during scale ontogenesis. Moreover, the regenerated basal plate exhibits an orthogonal “plywood” arrangement that is never seen in the embryonic scale where the “plywood” is of the intermediate type.
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  • 19
    ISSN: 1432-0878
    Keywords: Epididymis (marsupials) ; Ultrastructure ; Sperm maturation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ductus epididymidis of the tammar is lined by an epithelium composed of principal, mitochondria-rich, apical and basal cells, and intraepithelial leucocytes. The epithelium is structurally differentiated into 6 zones referred to as the initial segment, middle segment (3 subdivisions) and terminal segment (2 subdivisions). The occurrence of the initial, middle and terminal segments corresponds quite closely to the anatomical differentiation of the epididymis into a head, body and tail. The initial segment epithelium in the tammar is lower and has shorter and more slender stereocilia than in other mammals which have been described. Otherwise, the structure of the epithelium has similar characteristics in the tammar to that described in other mammals. Spermatozoa begin to develop the capacity for motility within the initial segment, but only show structural signs of maturation in the middle segment. The sperm head rotates through 90 degrees in the proximal subdivision of the middle segment. The cytoplasmic droplet is detached and spermatozoa develop the capacity for motility in the middle subdivision of the middle segment. The cytoplasmic droplets are phagocytosed by the epididymal epithelium of the middle segment. Sperm storage appears to be the main function of the terminal segment.
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  • 20
    ISSN: 1432-0878
    Keywords: Peptidergic neurotransmission ; Lymnaea stagnalis ; Immunocytochemistry ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Three neuronal systems of the pond snail Lymnaea stagnalis were immunocytochemically investigated at the ultrastructural level with the unlabeled peroxidase-antiperoxidase technique. Preliminary electrophysiological and cell-filling investigations have shown that a cluster of neurons which reacts positively with an antiserum against the molluscan cardio-active peptide FMRFamide, sends axons to the penis retractor muscle. In this muscle anti-FMRF-amide (aFM) positive axons form neuro-muscular synapses with (smooth) muscle fibers. The morphological observations suggest the aFM immunoreactive system to be involved in peptidergic neurotransmission. In the right parietal ganglion a large neuron (LYAC) is penetrated by aFM positive axons which form synapse-like structures (SLS) with the LYAC. The assumption that the SLS represent the morphological basis for peptidergic transmission is sustained by the observation that iontophoretical application of synthetic FMRFamide depolarizes the LYAC. The axons of a group of pedal anti-vasopressin (aVP) positive cells run in close vicinity to the cerebral ovulation (neuro-)-hormone producing cell system (CDC system) Synapses or SLS between the two systems were not observed. The fact that (bath) application of arg-vasopressin induces bursting in the CDC, may indicate that the vasopressin-like substance of the aVP cells is released non-synaptically.
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  • 21
    ISSN: 1432-0878
    Keywords: Photoperiods ; Pituitary gland, pars tuberalis ; Ultrastructure ; Phodopus sungorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Conspicuous cytological differences are found between specific secretory cells of the hypophysial pars tuberalis of Djungarian hamsters exposed to long and short photoperiods. The cells differ with respect to the shapes of perikarya and nuclei and show diverse amounts of secretory granules, lysosome-like bodies and glycogen.
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  • 22
    ISSN: 1432-0878
    Keywords: Pituitary gland, pars anterior (distalis) ; Gonadotrops ; Thyrotrops ; Ultrastructure ; Immunolabeling ; Teleosts
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Pituitaries of the African catfish (Clarias lazera) were studied with immunocytochemical methods, at the light-microscopic and ultrastructural levels, for the characterization and localization of gonadotropic and thyrotropic cells. Two immunostaining procedures with the use of different markers were carried out: (i) with peroxidase-antiperoxidase, (ii) with protein A-gold. In routinely stained sections for light microscopy two types of basophils were identified in the proximal pars distalis: (1) large, round, purple cells, and (2) small, angular, light-blue cells. Both types were immunolabeled with antibodies against Clarias α,β-gonadotropin (GTH) and salmon G100-GTH. Only the large basophils were immunolabeled with anti-carp β-GTH, whereas the small basophils were the only cells immunolabeled with anti-human thyrotropin beta subunit (anti-h TSH-β). It was concluded that the large basophils represent the gonadotrops and the small basophils the thyrotrops. At the ultrastructural level the immunostaining of the GTH-cells was confined to three types of inclusions: (i) secretory vesicles, (ii) globules, and (iii) electron-dense, membrane-bound irregular masses. Especially the protein A- gold method, in combination with the use of a highly diluted homologous antiserum, resulted in a distinct localization of GTH. The presence of two types of nerve fibres, synaptically contacting the gonadotrops, is discussed with regard to the presence of a peptidergic (stimulatory) and an aminergic (inhibitory) control of GTH-secretion.
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  • 23
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    Cell & tissue research 238 (1984), S. 497-502 
    ISSN: 1432-0878
    Keywords: D2 glycoprotein ; Adrenal gland ; Immunocytochemistry ; Ultrastructure ; Cell adhesion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ultrastructural localization of the glycoprotein D2 in rat adrenal gland was investigated using immunohistochemical methods, and D2 localization in cultures of adult bovine chromaffin cells was studied by immunofluorescence. D2 was found to be situated on nerve fibers passing through the adrenal cortex and in the medulla zone, and also on the surface of all chromaffin cells. In addition, it was strongly expressed on the surface of glial (Schwann) cells. Cortical cells were unreactive to the antiserum. In cultures, all adrenalin and noradrenalin [dopamine-β-hydroxylase (DBH)-positive] cells were surface labelled for D2. A less frequent second cell type was recognized in vitro which was DBH negative but D2 positive. Such cells were presumed to be Schwann cells. These data are discussed in terms of the developmental origin of the cells and with regard to the putative functional rôle of D2 in cell adhesion phenomena.
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  • 24
    ISSN: 1432-0878
    Keywords: Lymphocytes ; Phytohemagglutinin stimulation ; Nucleolar organizer region ; Three-dimensional reconstruction ; Ultrastructure ; Guinea pig
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ultrastructural changes in the spatial organization of nucleolar DNA in lymphocytes during phytohemagglutinin (PHA) stimulation was studied in guinea pigs by means of oxidized diaminobenzidine (DAB) at low pH as a differentially contrasting stain for nucleic acids and by the use of reconstruction of serial sections. The extended DNA filaments situated inside the fibrillar area originate from a large aggregation of heterochromatin, which is closely associated with the nucleolus, and from the perinucleolar shell of condensed chromatin. It is suggested that these two distinct regions of chromatin might be associated with different functions.
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  • 25
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    Cell & tissue research 235 (1984), S. 177-186 
    ISSN: 1432-0878
    Keywords: Retinal pigment epithelium ; Myeloid bodies ; Diurnal variation ; Morphometrics ; Ultrastructure ; Lipid metabolism ; Endoplasmic reticulum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Myeloid bodies (MBs) occur in the newt (Notophthalmus viridescens) retinal pigment epithelium (RPE) and are similar to areas of specialized endoplasmic reticulum found in a variety of other cell types. The function of these structures is unknown, although a role in lipid metabolism has been strongly suggested. Random samples from conventionally-fixed and sectioned newt RPE, obtained over a 24-hr cycle (LD 12∶12), were examined by electron microscopy. Myeloid bodies appear as stacks of flattened endoplasmic reticulum-associated saccules which increase in length and number as the RPE accumulates shed outer segment material, prior to increase in the amount of stored lipid. Associations of MBs with the nuclear envelope can be related to this increased length. Myeloid bodies decrease numerically in the cell as phagosomes are removed from the cytoplasm, but a decrease in mean sectional MB area, seen in the light phase, is counteracted in darkness where individual MBs are larger than those found in the light. The total sectional area of MBs within a cell and their mean length varied depending on the lighting condition; differences were also found between eyes after extended periods of continuous light and dark. Ribosomes were found in association with the surfaces of both flattened and circular MBs, but they were consistently more densely associated with the shorter concave surfaces of curved regions. A new hypothesis for MB function is presented, which is concerned with their role in isolating toxic lipids such as retinoids, which are accumulated during phagocytosis of shed outer segment tips, and which are capable of disrupting membrane-bound systems necessary for their eventual metabolism and safe storage.
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  • 26
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    Cell & tissue research 235 (1984), S. 691-693 
    ISSN: 1432-0878
    Keywords: Plasma cells ; Ultrastructure ; Immunology ; Myxinoids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Hagfishes, the most primitive vertebrates, are of special interest for the evolution of immune responses. Eptatretus stoutii, the Pacific hagfish, is able to mount cellular and humoral immune responses but all attempts to demonstrate in them the presence of plasma cells have failed. In the present study we demonstrate for the first time plasma cells identifiable by ultrastructural criteria in the pronephros, a primitive lymphohaemopoietic organ, of Myxine glutinosa, the Atlantic hagfish.
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  • 27
    ISSN: 1432-0878
    Keywords: Granular endoplasmic reticulum ; Ultrastructure ; Pinealocyte ; Mole
    Source: Springer Online Journal Archives 1860-2000
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    Notes: Summary Ten or more straight tubules, each of which consists of a double unit membrane of granular endoplasmic reticulum with a cylindrical profile, are joined side by side in a raft-like configuration in the cytoplasm of the pinealocytes of Japanese moles. They measure about 60 nm and 100 nm in their inner and outer diameters, respectively, and are often partially connected to unspecialized granular endoplasmic reticulum. Cisterns held between the inner and outer unit membranes with cylindrical profiles vary from 15 nm to 30 nm in width. Ensheathed portions of the cytoplasm are contiguous with cytoplasm outside the tubular units. The inner unit membranes of the tubules bear fewer ribosomal particles than the outer ones.
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  • 28
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    Cell & tissue research 236 (1984), S. 431-438 
    ISSN: 1432-0878
    Keywords: Satellite cells ; Satellite fibres ; Tail muscle ; Urodela ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The incidence and ultrastructure of satellite cells in the tail muscles of urodelan larvae were examined during development during which the number of satellite cells is gradually reduced. They are found more frequently in red than in the white fibres in all four stages examined (stage 53, 64, 66+ and juvenile). As development proceeds, intercellular space between satellite cell and muscle fibre is in general gradually extended and is mostly filled with basal lamina. Small muscle cells, satellite fibres, which are situated under the basal lamina of the parent fibre, are morphologically similar to satellite cells but contain a small amount of myofibrils. Three types of satellite fibres are distinguishable on the basis of differences in K2-EDTA-treated ATPase activity, width of Z line, and parent fibre type. Neuromuscular junctions are visible in satellite fibres.
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  • 29
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    Cell & tissue research 236 (1984), S. 465-470 
    ISSN: 1432-0878
    Keywords: Tendon ; Collagen fibrils ; Morphometry ; Ultrastructure ; Loading ; Mouse
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary This study was designed to gain more detailed morphological information on skeletal tendons in the course of adaptation to physical loading. The effect on collagen fibrils was investigated in 6-week-old mice by means of electron microscopy. Physical loading was performed on a treadmill 5 days a week for 1, 3, 5, 7 and 10 weeks. Morphometric analysis of collagen fibrils revealed the mean diameter, the diameter distribution, the number and the cross-sectional area. The principal observations included: 1. After one week of physical loading an increase in mean fibril diameter (30%, p≦0.01), in number (15%, p≦ 0.05), and in cross-sectional area (15%, p≦0.05), as well as a change in mean fibril diameter distribution. 2. From the third to the seventh week a fall under the level of the controls in mean diameter (26%, p≦0.01), in number (26%, p≦0.01), and a reduced cross-sectional area (17%, p≦0.01), accompanied by signs of splitting of individual collagen fibrils. 3. In the long-term study an increase in fibril number (29%, p≦0.01), a fall in mean diameter from 189 nm in the controls to 179 nm (p≦0.05) but no statistically significant change in the relative cross-sectional area (32%) per unit in comparison to unloaded tendons. The possible physiological implications of the findings are discussed in the light of several regulatory mechanisms known to appear during the course of physical loading in connective tissues.
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  • 30
    ISSN: 1432-0878
    Keywords: Steroids ; Vitellogenesis ; Metabolism ; Ultrastructure ; Teleosts
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Estradiol injections increase serum level of calcium, amino acid, glucose, protein, ammonia and creatinine in immature Epinephelus akaara, and also increase levels of total lipid, cholesterol, phospholipid and esterified fatty acids. Hepatic protein, glycogen and lipid concentrations also rise after estradiol treatment, and some hepatic enzymes participating in the metabolism of nitrogen, lipid and carbohydrate, show increased activity. Serum vitellogenin levels are increased. Testosterone treatment increases serum protein, total lipid, cholesterol, amino acid and ammonia levels, and also hepatic glycogen content, but in contrast to estradiol treatment, testosterone does not change serum vitellogenin, glucose, calcium, phospholipid, esterified fatty acid and creatinine levels, nor the hepatic lipid and protein content. A small number of hepatic enzymes shows an increased activity. Vitellogenic fish show biochemical changes similar to that of estradiol-treated fish, but are different from those of immature fish. Estradiol treatment induces ultrastructural changes in the hepatocytes of immature fish that are similar to those found in vitellogenic fish. These include a proliferation of rough endoplasmic reticulum and Golgi apparatus, and an increase in glycogen and lipid, all indicative of enhanced metabolic activity.
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  • 31
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    Cell & tissue research 236 (1984), S. 677-683 
    ISSN: 1432-0878
    Keywords: Interneuron ; Synaptology ; Ultrastructure ; Horseradish peroxidase ; Helix pomatia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The morphology, axonal arborization and ultrastructure of synaptic connections of the V21 giant neuron in the visceral ganglion of the snail Helix pomatia has been investigated following intracellular labelling with horseradish peroxidase. The V21 neuron establishes several afferent and efferent axo-axonic connections, mainly along the first half of the primary axon. Collaterals of 200–300 μm length originate from the primary axon, which shows further arborization, and both afferent and efferent synaptic contacts are formed on these fine axon profiles. Afferent and efferent contacts of the cell occur within very short distances of a few micrometers. On the basis of ultrastructure and vesicle and granule content, several afferent terminals can be distinguished on V21 labelled axon profiles. The majority of these afferent terminals resembles peptidergic-(neurosecretory)-like terminals. This finding supports the possible transmitter role of neuropeptides in the central nervous system of gastropods. Our results are consistent with and provide morphological evidence for recent electrophysiological observations suggesting that, in addition to integrating input, the V21 neuron functions as an interneuron in Helix central nervous system.
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  • 32
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    Cell & tissue research 237 (1984), S. 357-362 
    ISSN: 1432-0878
    Keywords: Leydig-Sertoli cell interaction ; FSH stimulation ; Ultrastructure ; Pig
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Interactions between Leydig and Sertoli cells, as well as a stimulatory effect of FSH on Leydig cell activity, have been reported in many studies. In order to investigate these interactions, the ultrastructure of immature pig Leydig cells under different culture conditions has been studied. When cultured alone in a chemically defined medium, there is a marked regression of the Leydig cell smooth endoplasmic reticulum and a swelling of the mitochondria. Addition of FSH or hCG does not prevent these phenomena. Co-culturing of Leydig cells with Sertoli cells from the same animal maintains the smooth endoplasmic reticulum at the level seen in vivo and in freshly isolated Leydig cells. The addition of FSH to the co-culture stimulates its development and increases Leydig cell activity, as assessed by an increase in hCG binding sites and an increased steroidogenic response to hCG. These results suggest that Sertoli cells exert a trophic effect on Leydig cells, and that the stimulatory effect of FSH on Leydig cell function is mediated via the Sertoli cells. These results reinforce the concept of a local regulatory control of Leydig cell steroidogenesis.
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  • 33
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    Cell & tissue research 238 (1984), S. 221-230 
    ISSN: 1432-0878
    Keywords: Fiber type ; Ultrastructure ; Stereology ; Stimulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary When fast-twitch skeletal muscles of the adult rabbit are subjected to continuous low-frequency activity by electrical stimulation of the corresponding motor nerves, the fibers undergo an ultrastructural transformation, so that after 6 weeks they have acquired an appearance typical of slow-twitch fibers. In the present study, stimulation was discontinued at this stage in order to follow the reverse transformation, in which the fibers recovered their original morphological characteristics under conditions of normal endogenous activity. Stereological techniques were used to assess the time course of this process over a period of 20 weeks in terms of fiber cross-sectional area, extent of T-system, thickness of the Z-band, and volume fraction of mitochondria in the fiber core. Fibers of transformed muscles were smaller than those of control muscles, but the differences were no longer evident after 9 weeks of recovery. After 2 weeks the T-system was still of limited extent, as is characteristic of slow-twitch fibers; it increased toward the amount typical of fast-twitch fibers between 2 and 4 weeks, and had reached its full extent by 12 weeks. The wide Z-bands characteristic of slow-twitch fibers were retained for 4 weeks, but the thickness had begun to decrease by 8 weeks and recovery was complete by 12 weeks. The mitochondrial volume did not increase during recovery, in contrast to the large increases which had been observed to take place between 2 and 6 weeks during the fast-to-slow transformation. Overall, the recovery of fast-twitch ultrastructural characteristics was complete, but followed a more extended time course, and involved less myofibrillar disruption at an intermediate stage, than the original fast-to-slow transformation.
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  • 34
    ISSN: 1432-0878
    Keywords: Ultrastructure ; Autoradiography ; Oocytes ; Nucleolus-like bodies ; Teleost
    Source: Springer Online Journal Archives 1860-2000
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    Notes: Summary Cytoplasmic granulo-fibrillar masses, usually termed nucleolus-like bodies (NLB) or nuages, have been described in several different cell types. They are sometimes associated with a mitochondrial arrangement, this association often being marked during certain phases of the oocyte cycle. In Xiphophorus helleri, NLB consist of fibrillar and granular material that gradually becomes more granular during meiotic prophase I, and is associated with mitochondrial arrangements during diplotene and dictyate of meiosis. Autoradiographic studies of uridine incorporation into the nucleolus and subsequently into NLB suggest that the latter represent a reserve of ribonucleoproteins that is later used in ribosomal maturation during vitellogenesis.
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  • 35
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    Cell & tissue research 238 (1984), S. 271-288 
    ISSN: 1432-0878
    Keywords: Compound eye ; Ultrastructure ; Grass shrimp, Palaemonetes pugio ; Light adaptation ; Dark adaptation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The cone cells and corneagenous cells possess extensive networks of smooth tubular endoplasmic reticulum that may be involved in optical reflectance and light-adaptational responses, respectively. The extracellular basal lamina of the basement membrane is confluent with glial cell capillary walls and may prove to be a viaduct for the transmission of hemolymph-borne substances to the retina or of retinal degradation products to the hemolymph. In addition to dense pigment granules, the distal pigment cells are shown for the first time to contain migratory reflecting platelets that are usually polymorphic in light-adapted eyes but are rectangular in dark-adapted eyes. In the latter these plates become aligned against the crystalline cones and presumably contribute to the reflection superposition optics of the grass shrimp. Dark-adapted retinular cells possess well-developed perirhabdomal cisternae, oblong or ovoid mitochondria, generally vesicular rough endoplasmic reticulum, and occasional, spherical, calcium-like intrarhabdomal inclusions. Light-adapted retinular cells possess poorly developed perirhabdomal cisternae, lamelliform rough endoplasmic reticulum, and condensed mitochondria frequently associated with lipid droplets and pigment granules. The cytoplasmic boundaries of the reflecting pigment cells expand into the extracellular spaces between individual ommatidial retinular cells during dark adaptation and recede to the interommatidial extracellular spaces during light adaptation. Cytoplasmic microfilament bundles found only at the bases of partially light-adapted rhabdomeric microvilli may be involved in microvillar shortening.
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  • 36
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    Cell & tissue research 235 (1984), S. 295-301 
    ISSN: 1432-0878
    Keywords: Tfm/Y mouse ; Submandibular gland ; Sexual ; dimorphism ; Androgens ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The fine structure of the submandibular gland of the mouse with testicular feminization (Tfm/Y) was studied by light and electron microscopy. The architecture of the Tfm/Y gland proved to be rather similar to that of the normal female mouse in both tubular ratio and structure. Granular convoluted tubular cells in Tfm/Y mice characteristically had fewer secretory granules and increased cytoplasmic vacuoles than normal littermates, suggesting an altered synthesis of secretory granules in this cell type of the Tfm/Y mouse. Moreover, there were differences in the ultrastructure of submandibular glands between Tfm/Y and normal female mice. In the gland of the Tfm/Y mouse, basal striations of the striated secretory tubular cells were not so developed and granular intercalated duct cells were less than those of normal females. These findings support the evidence that the secretory tubule of the mouse submandibular gland responds to androgens, resulting in accentuated development in the male, while also suggesting the possibility that the mouse submandibular gland is regulated by other factors which lead to the prominent sexual dimorphism observed in this gland.
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  • 37
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    Cell & tissue research 235 (1984), S. 463-466 
    ISSN: 1432-0878
    Keywords: Endocytosis ; Kidney (rat) ; Proximal tubule ; Apical vacuoles ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Following perfusion fixation of the rat kidney with glutaraldehyde the proximal tubule cells display small apical vacuoles, large apical vacuoles, and apical vacuoles in which a part of the limiting membrane is invaginated into the vacuole. These invaginated apical vacuoles occur more frequently in proximal convoluted tubules than in proximal straight tubules. One tubular cell may contain apical vacuoles of different sizes and stages of invagination, ranging from larger vacuoles with a wide lumen and a small area of invaginated membrane to smaller elements with no apparent lumen and a large area of invaginated membrane. Invaginated apical vacuoles lie either singly in the cytoplasm or close to the membranes of other apical vacuoles, but never in contact with the cell membrane or the membranes of lysosomes, endoplasmic reticulum, Golgi apparatus, mitochondria and peroxisomes. These findings suggest that the invaginated apical vacuoles are not fixation artifacts, but rather develop in living state in cells of the proximal tubule from spherical endocytotic elements.
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  • 38
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    Cell & tissue research 236 (1984), S. 339-343 
    ISSN: 1432-0878
    Keywords: Moulting ; Mechanosensory hair ; Chordotonal organ ; Ultrastructure ; Crustacea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The fine structure of hair mechanoreceptors in crayfish during moulting was investigated with special attention to the interface apparatus between cuticular hairs and sensory cells: the chorda. The chordae are lost with old exuviae at every moulting. They are drawn out from a moulting canal at the tip of the new hair. The chordae are regenerated from a material secreted by sheath cells after moulting. Therefore, the chorda is an inward projection of the cuticular exoskeleton, and it has direct contact with the sensory element, the scolopidium. The scolopidium has been found in both hair mechanoreceptors and subcuticular chordotonal organs in crustaceans, and is thought to be a primitive type of mechano-sensory transducing element. The present observation gives additional evidence for the homology of two sensory elements in arthropods, i.e., the cuticular hair sensilla and subcuticular chordotonal organs.
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  • 39
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    Cell & tissue research 236 (1984), S. 87-97 
    ISSN: 1432-0878
    Keywords: Iodination ; Membrane shedding ; Peroxidase ; Thyroid follicle cell ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Clusters of luminal dense bodies, limited by a triple-layered membrane, were found in all follicle lumina in thyroid glands of mice. After thyroxine treatment the number of luminal dense bodies increased, especially in the periphery of the lumen, where the intraluminal bodies often displayed a striking resemblance to microvilli. In hyperplastic goiters, obtained by feeding mice with propylthiouracil, luminal dense bodies were replaced by intraluminal vesicles. During goiter involution the vesicles were gradually replaced by luminal dense bodies; the presence of intermediate forms suggests that vesicles and dense bodies are basically the same formations. Luminal dense bodies were observed in colloid droplets indicating their removal by endocytosis. As demonstrated by electron-microscopic cytochemistry, luminal dense bodies contain a membranebound peroxidase, and electron-microscopic autoradiography after administration of 125I indicate that they possess an iodinating capacity. Our observations on mouse thyroid glands suggest that the luminal dense bodies, which appear as vesicles in hyperplastic glands, are formed by shedding of the apical plasma membrane of the follicle cell. The shedding process might be of importance for the turnover of plasma-membrane material.
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  • 40
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    Cell & tissue research 236 (1984), S. 171-180 
    ISSN: 1432-0878
    Keywords: Immunocytochemistry ; Ultrastructure ; Supraoptic nucleus ; Neuropil ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The neuropil located ventral to the SON was investigated by the use of immunoperoxidase staining for neurophysins, oxytocin and vasopressin, and electron miroscopy. The study was performed in six groups of rats: 1) control; 2) infusion of isotonic saline into the CSF; 3) infusion of hypertonic saline into the CSF; 4) drinking hypertonic saline for 4 days; 5) same as group 4 but injection of colchicine into the CSF on second day of dehydration; 6) salt loading for 3 months. In the control rats the ventral neuropil contained a few immunoreactive processes, the general morphology of which was completely different from that of the neurosecretory axons emerging from the SON at its dorsal aspect. In rats of groups 3 to 6 the ventral processes (VP) became loaded with neurosecretory granules, whereas the perikarya and axons were depleted. Based on their general morphology and reactivity pattern it is suggested that the VP are dendrites. Most of these “dendrites” were embedded in a glial cushion formed by the processes of a particular type of marginal glia. Some of these “dendrites” enveloped an arteriole penetrating the optic tract. All VP were rich in synaptic contacts. The possibility that the VP of neurosecretory cells may be functionally related to the subarachnoid CSF and the arteriolar blood flow is discussed.
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  • 41
    ISSN: 1432-0878
    Keywords: Peripolar cells ; Juxtaglomerular apparatus ; Newborn sheep ; Dexamethasone ; Ultrastructure ; Cytoplasmic granules
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In the renal juxtaglomerular region of newborn sheep, it was found that glomerular peripolar cells and their granules were very much larger than those found in fetal lambs or adult sheep. Similar peripolar cell hypertrophy was triggered in fetal lambs treated in utero with intraperitoneal injections of dexamethasone. Ultrastructurally, granules of peripolar cells from newborn lambs resembled closely the enlarged zymogen granules described in the pancreas of newborn rats. Such peripolar cell hypertrophy may reflect a functional adaptation of the kidney to immediate postnatal life.
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  • 42
    ISSN: 1432-0878
    Keywords: Development ; Enterocytes ; Fish ; Mitosis ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
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    Notes: Summary The processes of proliferation, cell division and differentiation of intestinal epithelial cells have been studied during development of the fish, Barbus conchonius. On the 3rd day, nearly all cells of the presumptive gut proliferate. Once the intestinal epithelium begins to differentiate, a decreasing percentage of proliferative cells can be found. On the 7th day, when intestinal folds start to develop, the proliferative cells become restricted to the future basal parts of the folds. Ultrastructural examination of 3H-thymidine-labeled cells and mitotic cells of 6-day-old larvae shows that functional enterocytes are proliferative. The same feature is suggested for older fish. Proliferating undifferentiated “dark” cells, characterized by many free ribosomes and a few organelles, are also present in the intestinal epithelium of larval fish; they are considered to be stem cells, mainly for goblet cells. Proliferating goblet cells and enteroendocrine cells were not observed. The latter cell type is scarce and has a long turnover time. A common feature of all these dividing cells is the presence of isolated spherical to cylindrical lamellar structures which may have lost contact with the cell membrane during prophase; they probably regain this contact by fusion with the cell membrane at the end of mitosis.
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  • 43
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    Cell & tissue research 237 (1984), S. 123-129 
    ISSN: 1432-0878
    Keywords: Pancreas, exocrine (rat) ; Ultrastructure ; Morphometry ; Development, ontogenetic ; Zymogen granules
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Pancreatic acinar cells of rats obtained at 1,2, 3, 5, 7 and 14 days of age were examined using fine structural and morphometric techniques. From 5 days of age onwards, the acinar cells were analysed twice per day, at 20.00 h and 08.00 h. The present study demonstrates changes in the average volume of the cell, nucleus and cytoplasm, and volume densities of various cytoplasmic organelles during the first two weeks after birth. During early postnatal life, the volume density of rER increases, whereas that of zymogen granules decreases. From 5 days of age onwards, the volume densities of these two organelles differ significantly at 20.00 h and 08.00 h. During the first 2–3 days after birth, inclusion body-like structures appear in the cytoplasm of acinar cells; they contain aggregated zymogen granules and, sometimes, amorphous structures or cytoplasmic organelles. These structures also occur in interstitial cells and cells located in the intercalated region between acinar and ductal epithelial cells. Serum level of α-amylase activity is high at birth, compared with other stages during the first three weeks. Degenerating acinar cells and cell debris can be seen in the acinar and ductal lumina during these stages, a feature suggesting holocrine secretion. Cellular polarity appears to be incomplete during the first two or three days after birth.
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  • 44
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    Cell & tissue research 238 (1984), S. 1-12 
    ISSN: 1432-0878
    Keywords: Lung ; Amphibia ; Ultrastructure ; Smooth muscle ; Extracellular matrix
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The lung of the giant salamander, Amphiuma tridactylum, is divided into respiratory alveoli by muscular septa that increase the surface area of the lung as well as provide a mechanism for its almost complete collapse during exhalation. The epithelium of the internal surface is of two types: respiratory, composed of a single layer of pneumocytes overlying anastomosing capillaries, and non-respiratory, composed of ciliated cells and mucus-secreting goblet cells. Non-respiratory epithelium covers the apical edges of the septa, whereas the respiratory epithelium lines the alveoli. The smooth muscle of the septa and walls of the lung was studied in preparations of uninflated and acetylcholine-contracted lung. The muscle cells are ultrastructurally similar to other types of smooth muscle but are surrounded by extraordinary amounts of extracellular matrix, containing collagen and elastic fibers and numerous fine fibrils of unknown composition. Smooth muscle in isolated lung strips contracted in a dose-dependent manner when treated with acetylcholine or methacholine; contraction was blocked by atropine. Responses of lung strips to adrenergic agents were limited; only high doses of adrenalin caused slight relaxation of previously contracted muscle. These observations support the hypothesis that contraction of pulmonary smooth muscle is responsible for the ventilatory efficiency of the lung.
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  • 45
    ISSN: 1432-0878
    Keywords: Subcommissural organ ; Secretory granules ; Secretory process ; Ultrastructure ; Natrix maura (Reptilia, Ophidia)
    Source: Springer Online Journal Archives 1860-2000
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    Notes: Summary Two different types of ependymal cells were found in the subcommissural organ (SCO) of Natrix maura. Most secretory cells showed morphological features resembling the general structure and ultrastructure of cells in the SCO of other vertebrates. This report describes a second population of cells lining a portion of the dorsal groove of the SCO. These cells were not selectively stained by chromalum-hematoxylin and, under the electron microscope, they were characterized by scarce surface differentiations, sparse apical cytoplasm and short basal processes. Flat, parallel cisternae of the rough endoplasmic reticulum produced vesicles that appeared to be transported to the well-developed Golgi apparatus. Dense secretory granules about 200 nm in diameter were found in the Golgi region. Similar granules were seen in the vicinity of the apical plasma membrane; some of them opened toward the ventricle. All these characteristics clearly differentiate this cell group from the other secretory cells lining the SCO laterally and ventrally.
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  • 46
    ISSN: 1432-0878
    Keywords: Teeth (Macropodinae) ; Enamel (opaque, translucent) ; Ultrastructure ; Enamel hardness
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Teeth of three macropod species, M. giganteus, W. bicolor and P. concinna, have been studied using the techniques of light microscopy, scanning- and transmission-electron microscopy and hardness measurement. Light microscope observations showed that the teeth of these species had a translucent enamel region close to the dentine and an outer opaque enamel region at the tooth's surface. These regions were not related to the presence or absence of tubules which are a characteristic feature of marsupial enamel. Hardness tests showed that the opaque enamel was softer than the translucent enamel. Scanning electron microscope observations revealed that there was no correlation between any particular prism packing or orientation and the opaque and translucent enamel regions. Transmission electron microscope observations showed that the translucent enamel region consisted of well defined prisms and well packed, lath-like crystals, whereas the opaque enamel was disrupted by voids (which ranged in size from enlarged micropores to about 2 μm in diameter in extreme cases) between crystals and some randomly oriented, loosely packed crystals. This disruption within the opaque enamel region was more common at prism boundaries but pockets of disrupted enamel were also found within prisms and interprismatic regions. The opacity of the enamel was caused by scattering of light from the voids. The ultrastructure of the opaque enamel region indicated that this region was hypomineralized; hardness tests and polarized light microscope observations were consistent with these results.
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  • 47
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    Cell & tissue research 238 (1984), S. 565-575 
    ISSN: 1432-0878
    Keywords: Pineal organ teleost ; Tissue culture ; Ultrastructure ; Indoles ; High performance liquid chromatography (HPLC)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ultrastructure and biochemistry of the goldfish pineal organ were examined in expiants cultured for 1, 3, and 6 days. All four cell types (photoreceptor, supportive, ganglion, phagocytic) were identified; they exhibited many of the characteristics of these cells in vivo. Exceptions included a gradual disorganization of the outer segments and reduction of synaptic ribbons in photoreceptors with time in culture. In addition, there was a marked proliferation of endoplasmic reticulum in both photoreceptor and supportive cells. The indoles 5-hydroxytryptophan, serotonin, 5-hydroxyindoleacetic acid, 5-methoxytryptophol, and melatonin were separated in expiants by high performance liquid chromatography using electrochemical detection. Serotonin levels could be depleted by p-chlorophenylalanine and elevated by nialamide or by adding 5-hydroxytryptophan to the culture medium. These findings suggest that organ culture may be a useful model for study of regulatory processes related to the photoneuroendocrine functions of the teleost pineal organ.
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  • 48
    ISSN: 1432-0878
    Keywords: Innervation ; Smooth muscle ; Fish ; Kidney ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The fine structure of the collecting tubules of the trout and killifish kidney was studied. These tubules are surrounded by layers of smooth muscle cells which are commonly innervated. The nerve terminals contain synaptic vesicles and, occasionally, a few dense-cored granules as well. Capillaries occur in the connective tissue space between these smooth muscle cells and the collecting tubule. Epithelial cells of the collecting tubules contain abundant mitochondria and a well developed membrane system displaying parallel arrays, and were considered to be actively involved in the transport of materials. In the trout, the collecting tubules contain peculiar cells in addition to regular tubule cells. The fine structure of these peculiar cells is highly reminiscent of that of gill chloride cells. The significance of these findings may be summarized as follows: If the smooth muscles around the collecting tubule contract under neural influence, intratubular pressure may be increased and, thus affect glomerular filtration rate. The contraction of these muscles may also cause the collapse of peritubular capillaries, affecting the transport activity of tubule cells.
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  • 49
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    Cell & tissue research 238 (1984), S. 621-626 
    ISSN: 1432-0878
    Keywords: Catecholamines ; Pituitary innervation ; Radioautography ; Ultrastructure ; Goldfish
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The monoaminergic innervation of the goldfish pituitary gland was studied by means of light- and electronmicroscopic radioautography after in vitro administration of 3H-dopamine. The tracer was specifically incorporated and retained by part of the type-B fibers innervating the different lobes of the pituitary. In the rostral pars distalis labeled fibers were most frequently observed in contact with the basement membrane separating the neurohypophysis and the adenohypophysis. In the proximal pars distalis and the pars intermedia, labeled profiles were detected in the neural tissue and in direct contact with the different types of secretory cells. According to the previous data concerning the uptake and retention of tritiated catecholamines in the central nervous system, it is assumed that the labeled fibers are mainly catecholaminergic (principally dopaminergic). This study provides morphological evidence for a neuroendocrine function of catecholamines in the goldfish.
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  • 50
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    Cell & tissue research 238 (1984), S. 635-642 
    ISSN: 1432-0878
    Keywords: Liver ; Endothelium ; Kupffer cells ; Peroxidase ; Cytochemistry ; Ultrastructure ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Rat liver fixed by perfusion with low glutaraldehyde concentrations was incubated in diaminobenzidine-containing medium to stain for peroxidase. Endogenous peroxidatic activity was found not only in Kupffer cells but also in the endothelial cells lining the sinusoids and central veins. The reaction product was localized in the nuclear envelope and endoplasmic reticulum. The peroxidatic activity in endothelial cells showed a concentration-dependent sensitivity to glutaraldehyde: in liver samples fixed with 0.25% glutaraldehyde, approx. 23% of the sinusoidal endothelial cells and 65% of central vein endothelium were peroxidase-positive; with 0.5% glutaraldehyde, only approx. 8% of the sinusoidal endothelial cells contained detectable amounts of the reaction product; with 1.5% glutaraldehyde all endothelial cells were consistently peroxidase-negative. No peroxidatic activity could be found in liver endothelial cells following isolation by centrifugal elutriation. Endothelial cell peroxidase may possibly be involved in defense responses of liver and/or, as a part of prostaglandin synthase system, in prostanoid production.
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  • 51
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    Plant systematics and evolution 146 (1984), S. 145-162 
    ISSN: 1615-6110
    Keywords: Chlorophyceae ; Spermatozopsis similis ; Ultrastructure ; green flagellate ; flagellar apparatus ; function ; phylogeny
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The ultrastructure of the flagellar apparatus of the naked, biflagellate green algaSpermatozopsis similis Preisig & Melkonian has been studied in detail using an absolute configuration analysis. The two basal bodies are displaced by 350 nm in the 1/7 o'clock direction and do not overlap proximally. They are interconnected by a principal distal connecting fibre consisting of a bundle of 5–8 nm filaments and possibly two proximal striated connecting fibres. The flagellar root system is cruciate (5-2-5-2 or 4-2-4-2 system) and contains a prominent continuous system I fibre overlying the two opposite two-stranded roots. A system II fibre is absent. Pronounced structural differences have been observed in the flagellar apparatus ultrastructure at two types of flagella orientation: During backward swimming basal bodies are parallel, the distal connecting fibre is extremely contracted; during forward swimming basal bodies assume various angles (from 20° to 180°) and the connecting fibre is about five times longer compared to the contracted state. The function of the connecting fibre as a contractile organelle and the mechanism of its contraction are discussed. On the basis of the flagellar apparatus ultrastructure,Spermatozopsis similis is related toChlamydomonas-type green algae.
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  • 52
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    Plant systematics and evolution 147 (1984), S. 189-203 
    ISSN: 1615-6110
    Keywords: Angiosperms ; Ericaceae ; Onagraceae ; Mimosaceae ; Musaceae ; Ultrastructure ; function of pollen connecting threads and viscin threads ; palynology ; pollination ecology
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    Topics: Biology
    Notes: Abstract Viscin threads and other pollen connecting threads of some angiosperm families were investigated, especially those ofEricaceae. According to the definition adopted, viscin threads are ± long exinous processes which consist of exinous material and connect pollen grains or tetrads. Such viscin threads are found within theOnagraceae, Caesalpiniaceae, Ericaceae, andMimosaceae only. While they differ in structure and composition, they always consist of sporopollenin and exhibit a very strong stickiness, even after all viscid substances have been removed by acetolysis. In contrast, the pollen connecting scleroprotein threads ofOrchidaceae and the cellular threads ofStrelitzia reginae Aiton. (Musaceae) are not connected with the exine surface, are destroyed by acetolysis, and thus do not correspond to viscin threads.
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  • 53
    ISSN: 1615-6102
    Keywords: Cold acclimation ; Exocytotic extrusions ; Freeze-fracture ; Isolated rye protoplasts ; Lipid bodies ; Osmotic contraction ; Plasma membrane ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Osmotic contraction of protoplasts isolated from cold acclimated leaves ofSecale cereale L. cv. Puma results in the formation of exocytotic extrusions of the plasma membrane. Numerous knobs or polyps were observed on the surface of the protoplasts with scanning electron microscopy. In thin sections, the extrusions were bounded by the plasma membrane with a densely osmiophilic interior. Cross-fracturing of the extrusions revealed aparticulate bodies within, a further indication that the interior of the extrusions was predominantly lipid material. Freeze-fracture of the plasma membrane suggests a possible source of this lipid material. Following osmotic contraction, the particle density on the plasma membrane protoplasmic face (PFp) increased, being reflected in both a substantial increase in paracrystalline arrays and an increase in the particle density in non-crystalline regions. This increase in particle density indicates that lipid material is preferentially lost from the plasma membrane during contraction. The density on the exoplasmic face (EFp) did not change. Together, these findings suggest that during hypertonic contraction of acclimated protoplasts, lipid material is preferentially subducted from the plasma membrane and sequestered into lipid bodies (the osmiophilic regions). The formation of lipid bodies and extrusions was readily reversible. Following osmotic expansion of acclimated protoplasts, the extrusions were retracted back into the plane of the plasma membrane.
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  • 54
    ISSN: 1615-6102
    Keywords: Anemia phyllitidis ; Chloroplast ; Gametophyte ; Metronidazole ; Ultrastructure
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    Topics: Biology
    Notes: Summary Metronidazole inhibits cell division in gametophytes of the fernAnemia phyllitidis without changing morphogenetic patterns. Simultaneously the sensitivity of the prothallia against gibberellins which substitute for the natural sexual pheromone “antheridiogen A”, is increased. The inhibition of cell division is accompanied by a loss of chlorophyll and by severe changes in the ultra-structure of the chloroplasts.
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  • 55
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    Protoplasma 113 (1982), S. 189-192 
    ISSN: 1615-6102
    Keywords: Brassica napus ; Membrane ; Nucleolus ; Nucleus ; Ultrastructure ; Vacuole
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    Topics: Biology
    Notes: Summary Vacuole-like structures were found in the nuclei of root tip cells ofBrassica napus. The cells containing the unusual nuclear inclusions were found to be adjacent to zones of degenerating cells. Such groups of cells occurred irregularly in the meristematic regions of the young root tips. The possibility that they represent changes which have occurred in old seeds is discussed. The “vacuole-like” structures seen in the cells adjacent to the degenerating zones were bounded by a membranous layer 12 nm thick. This is thicker than most cellular membranes. The “vacuoles” frequently contained inclusions and showed similarities to protein bodies reported elsewhere. The structures are thought to represent rearrangements of cell products which may have accumulated through an imbalance of metabolism in consequence of the imminent cell degeneration.
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  • 56
    ISSN: 1615-6102
    Keywords: Aspergillus nidulans ; Aspergillus giganteus ; Hyphal apex ; Ultrastructure ; Woronin body
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    Topics: Biology
    Notes: Summary The hyphal tip ultrastructure ofAspergillus nidulans andAspergillus giganteus indicates that their apical organization is very similar to that found in other filamentous fungi. Both species have an area immediately behind the hyphal apex free of all large organelles and containing a high concentration of vesicles. InA. giganteus only one size class of vesicle is clearly evident, with a mean diameter of 72 nm. InA. nidulans two size classes of vesicle were found, with mean diameters of 75 nm and 31 nm. A Spitzenkörper is evident inA. nidulans as an area very close to the tip containing only the smaller vesicles. InA. giganteus one or more apparently mature Woronin bodies were found within the first 1 μm of some hyphal apices. The possible significance of their presence is discussed.
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  • 57
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    Protoplasma 119 (1984), S. 55-61 
    ISSN: 1615-6102
    Keywords: Rhodophyta ; Nitophyllum ; Membranous body ; Plastid ; Red algae ; Thylakoidal origin ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The fine structure of plastids in the early stages of differentiation has been studied during the carposporogenesis of the red algaNitophyllum punctatum (Stackh.) Grev. A membranous body has been found in the plastidial matrix, which shows connections either with thylakoids, or with the plastidial genophore. More than one membranous body may be present and in some instances they show a morphological relationship also with the plastidial limiting membranes. The presence of such bodies has been observed also in fully differentiated plastids in a number of other red algae currently under study. It has been shown that the plastidial envelope may release in the matrix vesicles that give rise to the single thylakoids typical of the red algal plastids.
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  • 58
    ISSN: 1615-6102
    Keywords: Plastid greening ; Zea mays ; Ultrastructure
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    Topics: Biology
    Notes: Summary The effects of light intensity and cell age on the greening of etioplasts were studied in seedlings of maize. We could see that in the youngest tissues examined by us the etioplast greening is very fast and occurs according to a particular pattern which is characterized by the contemporary presence of grana and large non crystalline prolamellar bodies. On the contrary, in the oldest examined tissues the etioplast greening is slow and the formation of grana appears to be delayed and subsequent to the using up of the prolamellar bodies. In the young tissues the intensity of the light mainly affects the duration of the lag-phase preceding the chlorophyll accumulation, while in the old tissues it also affects the total amount of chlorophyllous pigments, the restraining effect of the light appearing amplified by a concomitant restraining effect of cell age.
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  • 59
    ISSN: 1615-6102
    Keywords: Meiosis ; Microtubules ; Polarity ; Ultrastructure ; Mosses
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    Topics: Biology
    Notes: Summary An extensive system of microtubules develops during meiotic prophase in the mossRhynchostegium serrulatum (Hedw.)Jaeg. &Sauerb. Development of the cytoskeleton can be traced to early prophase when the nucleus is acentric and the single plastid divides into four plastids. The cytoskeletal microtubules are associated with equidistant positioning of the four plastids at the distal tetrad poles and with migration of the nucleus to a central position in the sporocyte. The cytoskeleton, which interconnects plastids and encloses the nucleus, contributes to the establishment of moss sporocyte polarity. Just prior to metaphase I evidence of the prophase cytoskeleton is lost as the bipolar metaphase I spindle develops in association with discrete polar organizers located in opposite cleavage furrows between plastids.
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  • 60
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    Protoplasma 113 (1982), S. 10-22 
    ISSN: 1615-6102
    Keywords: Diatom ; Motility ; Mucopolysaccharide ; Secretion ; Staining ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Generation of movement in benthic diatoms is thought to be intimately associated with secretion at the raphe, a slit in the silica cell wall. The presence and distribution of extracellular substances and their source was investigated cytochemically by transmission electron microscopy. Extracellular material, possibly-acid mucopolysaccharide, was observed consistently within the entire length of the raphe of both valves and also as a sheath enveloping the silica frustule. Such quantities of extracellular material are absent in conventionally fixed motile diatoms. Numerous cytoplasmic vesicles, with fibrillar contents, distributed peripherally but concentrated along the raphe and at the cell poles, react strongly with a polysaccharide specific stain; their distribution in the cell and polysaccharide content suggest these may be the source of raphe and sheath material. Results support the most recent theories on the mechanism of locomotion in outline only; the details cannot be clarified. Localization procedures using alcian blue and silver staining of peroxidised sections are discussed briefly.
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  • 61
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    Protoplasma 120 (1984), S. 72-83 
    ISSN: 1615-6102
    Keywords: Fungus ; Mitosis ; Entomophthoraceae ; Erynia neoaphidis ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary An account of mitosis in the aphid-pathogenic, entomophthoraceous fungusErynia neoaphidis is presented. The mitotic apparatus is characterized by a closed, intranuclear, polarized spindle. Chromosomes are permanently attached by kinetochore microtubules (kcMTs) to the poles during mitosis. The spindle develops as the spindle pole bodies migrate and separate. At metaphase the eccentric spindle contains only kcMTs and is located in a relatively chromatinfree zone. Paired sister kinetochores are arranged in a broad metaphase plate. During anaphase kcMTs shorten, astral and nonchromosomal microtubules develop and elongate and the interpolar distance increases.
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  • 62
    ISSN: 1615-6102
    Keywords: Entomophaga aulicae ; Fungi ; Mitosis ; Nucleus associated organelle ; Taxonomy ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Nuclei in protoplasts ofEntomophaga aulicae contain abundant condensed chromatin and a large central nucleolus. The metaphase spindle occupies a small eccentric area of the nucleus while the remainder of the nucleus is filled with condensed chromatin. Small portions of condensed chromatin are aligned along a broad metaphase plate and connected to the spindle poles by kinetochore microtubules. The nucleus associated organelle (NAO) is a solid barlike structure which lies at the spindle poles and is closely associated with the outer membrane of the nuclear envelope. Comparison of the nuclear characteristics ofE. aulicae with those of other members of theEntomophthorales supports the separation of theEntomophthoraceae from theBasidiobolaceae andAncylistaceae. Further comparison of details of nuclear division in theEntomophthoraceae, specifically NAO morphology, may be useful in helping to delineate evolutionary lines within the family.
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  • 63
    ISSN: 1615-6102
    Keywords: Freeze-fracture ; Isolated rye protoplasts ; Osmotic contraction ; Plasma membrane-derived vesicles ; Ultrastructure
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    Topics: Biology
    Notes: Summary Following osmotic contraction of isolated rye protoplast (Secale cereale L. cv. Puma) that results in nearly a 50% reduction in volume, the plasma membrane was smooth, with no folding or pleating. Instead, deletion of plasma membrane occurred and numerous cytoplasmic vesicles were observed. As a result, the area of the plasma membrane was reduced by approximately 40%. Thin sections revealed that the cytoplasmic vesicles were membrane bound and not merely voids in the cytoplasm. High resolution video microscopy revealed the extent of vesiculation showing large clusters of cytoplasmic vesicles following osmotic contraction. Labeling the plasma membrane with fluorescein-Con-A prior to hypertonic contraction suggested that the cytoplasmic vesicles were derived from the plasma membrane. Freeze-fracture particle density on both the protoplasmic (PFp) and exoplasmic face (EFp) of the plasma membrane remained unchanged following contraction, which is consistent with a unit-membrane deletion into cytoplasmic vesicles. Upon partial re-expansion of the protoplasts, thin sections showed that the vesicles remained in the cytoplasm. These results using osmotic manipulation confirm earlier observations of isolated protoplasts at the light microscope level. Upon contraction plasma membrane is deleted into cytoplasmic vesicles, which are not readily reincorporated into the plasma membrane upon expansion. Lysis occurs before the original volume and surface area are regained.
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  • 64
    ISSN: 1615-6102
    Keywords: Fungi ; Gilbertella persicaria ; Membranes ; Mitochondria ; Organelle isolation ; Plasma membrane ; Ultrastructure ; Vacuoles
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    Notes: Summary Methods are described for isolating and identifying subcellular membranes from walled hyphae ofGilbertella persicaria. Differences in thickness and symmetry of membranes and in contents of vesicles were used to distinguish different types of membranes. Mitochondria, vacuoles, plasma membrane, and vesicles with attached ribosomes from homogenized germlings equilibrated at the 1.2/1.4 M interface in discontinuous sucrose gradients. Accelerated flotation in centrifuged Ficol-sucrose gradients resulted in the additional separation of the mixed membranes into three fractions: one contained predominantly intact mitochondria, another was composed of vacuoles and vesicles coated with ribosomes, and a third was enriched in plasma membranes. Based upon morphometric analysis, these fractions contained 92% mitochondria, 53% vacuoles, and 89% plasma membranes, respectively. The source of vesicles coated with ribosomes was investigated since rapidly growing hyphae ofG. persicaria contained little rough endoplasmic reticulum as compared with other classes of membranes. Reconstruction from electron micrographs of mitochondrial fragmentation and vesiculation suggested that most of the ribosome-coated vesicles originated from disrupted mitochondria rather than from rough endoplasmic reticulum. The study demonstrates the utility of ultrastructural markers to identify membranesin vitro independent of, or as an adjunct to, cytochemical and biochemical markers.
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  • 65
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    Protoplasma 112 (1982), S. 26-36 
    ISSN: 1615-6102
    Keywords: Aneilema ; Commelina ; Cytochemistry ; Evolution ; Papillae ; Pollination ; Secretion ; Stigmas ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The stigmas of species inAneilema andCommelina are trifid and comprise elongate papillae. Progressive degeneration of papular cells is observed in stigmas from open flowers and at anthesis papillae may be moribund and collapsed. Fluid emanating from the hollow style flows onto the surface through ruptures in the cuticle at the interpapillar junctions into the interstices at maturity. This secretion stains positively for protein. Stigmas are of the “wet” type. The cuticle overlying the papillar cells is ridged and at the final stages prior to flowering this cuticle becomes detached from the underlying cellulosic wall. The sub-cuticular space so formed is filled with secretion. InAneilema species detachment of cuticle is at the papillar tip and along the lateral walls. InCommelina species the anticlinal walls of adjacent papillae are strongly attached for much of their length and thus detachment of cuticle is restricted to the papillar tip. The cell wall at the tip in both genera may proliferate forming a rudimentary transfer-cell type wall. The secretion is considered to be produced by the papillar cells. It is PAS positive but fails to stain for protein and in both the light and electron microscopes appears heterogenous. Pollen attachment, hydration, germination and early tube growth are very rapid following self-pollination, the pollen tubes entering the neck of the style within ten minutes of attachment. A unique character combination involving pollen and stigmas in these genera indicates a monophyletic origin.
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    Protoplasma 112 (1982), S. 81-91 
    ISSN: 1615-6102
    Keywords: Didymium iridis ; Microcyst-encystment ; Ultrastructure ; Differentiation ; Myxomycete
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Myxamoebae ofDidymium iridis were removed from the bacterial food source and induced to encyst by transfer to 10 mM phosphate buffer. After 24 hours of induction approximately 90% of the myxamoebae had differentiated into microcysts. The kinetics of encystment were not significantly affected by pH or osmolarity of the encystment medium. Early stages of encystment were distinguished by the appearance of autophagic vacuoles and an extracellular “slime-like” sheath. The outer wall layer, consisting of dense fibrils, was unevenly deposited after 4 hours. An electron-lucent, second wall layer appeared between 5–10 hours followed by a densely packed, third wall layer adjacent to the plasma membrane. Wall formation appeared to involve smooth-membraned vesicles of possible Golgi origin. The vesicle contents and outer wall layer reacted with the periodic acid-silver methenamine stain for polysaccharide. The density of intramembrane particles of the protoplasmic fracture face increased during encystment with a gradual formation of aggregates of particles.
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  • 67
    ISSN: 1615-6102
    Keywords: Discophrya ; Tentacle contraction ; Cations ; Calcium ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Discophrya collini is a suctorian protozoan with contractile tentacles containing a microtubule-lined canal and microfilaments. The effects of a range of cations on tentacle contraction and ultrastructure have been determined. Treatment with 80 mM CaCl2 and 95 mM MgCl2 causes contraction to 28% and 57% of the control length respectively. Re-extension takes over 4 hours in the culture medium, but CaCl2-treated tentacles are re-extended after a 5 minutes treatment with 10−2 M EDTA or 5 × 10−3 M EGTA. CuCl2 causes a significant contraction at 10−5 M (to 77%); LaCl3 at 10−4 M (to 65%); ZnCl2 at 10−2 M (to 65%), but BaCl2, CoCl2, MnCl2, NiCl2, and SrCl2 cause significant changes only at 10−1 M. The cytoplasm of CaCl2-treated cells contains two forms of membraneous structures when viewed in TEM; that of MgCl2-treated cells reveals granular areas of medium electron density. None of these features are seen in control cells. The microtubules of the tentacle canal appear to be intact upon its retraction into the cell with no change occurring in the numbers or relative positions of the microtubules. The tentacle cortex is wrinkled. It is suggested from this and previous work that tentacle contraction may be mediated by a microfilament-based mechanism, and that calcium may be involved.
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  • 68
    ISSN: 1615-6102
    Keywords: Fungus ; Zoospore ; Ultrastructure ; Membranes
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    Topics: Biology
    Notes: Summary Determining how the orientation and association among organelles are maintained within zoospores of theChytridiales is important to understanding the control of zoospore motility. Zoospores of the aquatic fungi,Chytriomyces aureus andC. hyalinus, contain microbody-lipid globule complexes with an elongate microbody adjacent to the portion of a lipid globule facing the cell's interior and a fenestrated cisterna (the rumposome) opposed to the surface of the lipid globule toward the plasma membrane. Mitochondria are intimately associated with the microbody. Electron microscopy of the microbody-lipid globule complex fixed in glutaraldehyde and osmium tetroxide, with or without tannic acid, reveals cross-linking bridges connecting the rumposome to the plasma membrane, to the microbody, and to microtubules of the rootlet extending from the kinetosome. It is concluded that these bridges are responsible, at least in part, for the consistent location of the microbody-lipid globule complex in the zoospore body. The possible role of the rumposome as a receptor organelle is discussed.
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  • 69
    ISSN: 1615-6102
    Keywords: Secretion ; Vesicles ; Ultrastructure ; Cultured cells
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    Topics: Biology
    Notes: Summary Callus-derived suspension cultures of oats dramatically increase the viscosity of the culture media after one month in culture. Colorimetric assays for sugars and protein, as well as measurements of viscosity, suggest that the released material is a long-chain polysaccharide, probably a pectinaceous substance. These cells grow slowly in liquid culture, yet despite their low cell density, they are able to increase the viscosity of the media several fold within seven days after media transfer. Ultrastructural observations show that oat cells have features common to actively-secreting cells; especially evident are numerous dictyosomes with hypertrophied cisternae. Using a combination of filtering and centrifugation techniques we were able to recover large numbers of intact secretory vesicles. The interior of the vesicles stain with periodic acid-silver hexamine, and colormetric analysis of the vesicle pellet for total sugars confirms the presence of polysaccharides in this vesicle fraction. Because of the uniformity of these cells, the high rate of secretion, and the accessability of a large vesicle population, this culture system is'a useful model for studying the secretory process in plant cells.
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    Protoplasma 120 (1984), S. 61-71 
    ISSN: 1615-6102
    Keywords: Fungus ; Spindle pole body ; Entomophthoraceae ; Erynia neoaphidis ; Ultrastructure ; Replication
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A detailed account of the ultrastructure and behaviour of the spindle pole body (SPB) of the entomophthoraceous fungusErynia neoaphidis is presented for the first time. The SPB consists of extranuclear (ENC) and intranuclear (INC) components. The ENC is a “saucepan-shaped” structure which lies in a pocket of the nuclear envelope. It is composed of a forked, fibrillar “handle” and a shallow, cylindrical “pan”. The “pan” has a wall of two layers, both of which are thickened with a regular periodicity so that they appear to be “beaded”. It is postulated that the “pan“ is formed from rough endoplasmic reticulum and that it synthesizes the amorphous, electron-dense material coating the ENC. The INC is a “saucer-shaped”, electron-dense plaque in which the ends of the spindle microtubules terminate. During metaphase, a “clear zone” separates the INC from the nuclear envelope and persists until telophase. The roles of the amorphous, electron-dense material and the “clear zone” as well as the method of SPB replication are discussed.
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  • 71
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    Protoplasma 121 (1984), S. 65-76 
    ISSN: 1615-6102
    Keywords: Blastocladiales ; Chytridiomycetes ; Coelomomyces ; Cytoplasmic cleavage ; Gametogenesis ; Mosquito-copepodpathogen ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The ultrastructure of gametogenesis was studied inCoelomomyces dodgei Couch (Blastocladiales, Chytridiomycetes), an obligate parasite of anopheline mosquito larvae and the copepod,Acanthocyclops vernalis. In infected copepods reared under a 16/8 hours light/dark photoperiod at 25 +2 °C., the gametophyte develops over a period of approximately seven days, and gametogenesis is triggered by the onset of the dark period during the last day of development. The initial step of gametogenesis is the elongation of the centriole to form the kinetosome, and measuring time from the onset of the final dark period (0 hours), this occurs prior to the beginning of the light period (8 hours). Subsequently, small vesicles that appear to originate from elements of the rough endoplasmic reticulum (rER) fuse at the distal end of the kinetosome forming the flagellar vesicle into which the axonemal microtubules elongate to form the flagellum (8–12 hours). Similar small vesicles apparently also derived from rER align in planes and fuse to form cleavage furrows which delineate the gamete initials (12–14 hours). As the gamete initials begin forming, the mitochondria within each initial fuse to form a single mitochondrion that associates with the lipid globules and microbodies forming the microbody-lipid globule complex (12–16 hours). The time elapsed between the formation of the flagellar vesicle to the release of mature gametes from the copepod host is about 8.5 hours. No differences were observed in the processes or timing of gametogenesis in male and female gametophytes.
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    Protoplasma 121 (1984), S. 77-86 
    ISSN: 1615-6102
    Keywords: Blastocladiales ; Coelomomyces ; Gametes ; Mosquitocopepod pathogen ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary As part of an investigation on the developmental biology ofCoelomomyces dodgei Couch (Blastocladiales, Chytridiomycetes), the ultrastructure of the male and female gametes was studied. The nucleus is central and conical in shape except for a basal spur that curves back towards the large plate-like mitochondrion. A nuclear cap of ribosomes sits on the flat anterior end of the nucleus. Approximately seven lipid globules are partially embedded in the mitochondrion and are interconnected by membrane cisternae. The lipid globules are covered by a single fenestrated microbody and a backing membrane lies between the microbody and the gamete plasma membrane. The kinetosome is at the base of the nucleus and is connected to a single, posterior, whiplash flagellum. A nonkinetosomal centriole is absent. In the peripheral cytoplasm of both mating types there is a paracrystalline body of unknown composition and function. No significant ultrastructural differences were found between the male and female gametes.
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  • 73
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    Protoplasma 122 (1984), S. 203-221 
    ISSN: 1615-6102
    Keywords: Actinia fragacea ; Granular amoebocytes ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The structure of granular amoebocytes of the intertidal sea anemoneActinia fragacea (Cnidaria: Anthozoa) has been investigated using the electron microscope. Cells from the gonads of large, intact individuals were studied in most detail, but other regions of the anemone were also examined. The amoebocytes are cells of variable appearance which are widely distributed both in the mesogloea and in the epithelial cell layers. They contain numbers of characteristic dense granules, which may enclose spherical cores of greater or lesser electron density. They also contain rough endoplasmic reticulum, Golgi apparatus and a range of inclusions, some of which may have lysosomal origins. They may contain extensive deposits of glycogen, and usually smaller quantities of lipid droplets. They may take on a variety of forms, depending partly on their location within the various types of mesogloea and epithelia. The amoebocytes appear to be motile and phagocytic, and may also be involved in the storage and transport of glycogen. They are involved with gametogenesis, both during the development of the oocytes and spermatogenic cysts and during the resorption of degenerating gametes. Their possible role in the secretion or maintenance of the mesogloea remains uncertain. No evidence of amoebocytes differentiating into other cell types was obtained.
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  • 74
    ISSN: 1615-6102
    Keywords: Chromosome fragments ; Holokinetic chromosomes ; Karyomeres ; Nucleolar material ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Chromosomes and nucleoli in the karyomeres of cleavage eggs of the arrhenotokous spidermiteTetranychus urticae Koch were treated with a silver-staining procedure for nucleolar material to establish the number of nucleoli and of the chromosomes that produce them. Each of the three holokinetic chromosomes of the haploid chromosome complement produces nucleolar material. This is confirmed by observations on the ultrastructure of karyomeres in serial sections of interphase cleavage divisions. These findings are thought to be in agreement with facts from previous radiation research and may help to explain the fate of induced fragments in holokinetic chromosomes.
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  • 75
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    Protoplasma 123 (1984), S. 104-115 
    ISSN: 1615-6102
    Keywords: Constrictive binary fission ; Cyanobacteria ; Development ; Multiple fission ; Septate binary fission ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary An ultrastructural examination of cell division in two baeocyte producing cyanobacteria,Pleurocapsa minor andDermocarpa violaceae, reveals two distinct patterns of binary (transverse) fission. Septate binary fission, inPleurocapsa minor, involves centripetal synthesis and deposition of the mucopolymer cell wall layer (L 2). The ingrowth of the cytoplasmic membrane and L 1 cell wall layer, along with the synthesis of the L 2 cell wall layer, results in the formation of a prominent septum. Partitioning of the cell occurs by the constriction of the outer cell wall layers (L 3 and L 4) through the septum. InDermocarpa violaceae, constrictive binary fission occurs by the simultaneous ingrowth or constriction of the cytoplasmic membrane and all cell wall layers (L1, L2, L3, L4). Septate and constrictive binary fission may proceed symmetrically (medially) or asymmetrically (nonmedially). Multiple fission occurs regularly inDermocarpa violaceae and provides for a rapid means of reproduction when compared to binary fission. Successive radial and tangential divisions of the protoplast result in formation of many small daughter cells (baeocytes). The process of multiple fission is similar to septate binary fission with reduced septa being formed. However, constriction of the outer cell wall layers, through the septa, proceeds concurrently with septum formation.
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  • 76
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    Protoplasma 121 (1984), S. 199-208 
    ISSN: 1615-6102
    Keywords: Psychotria ; Leaf nodules ; Calyx nodules ; Symbiosis ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The occurrence and structure of calyx nodules in the flowers of two leaf nodulated rubiaceous speciesPsychotria punctata Vatke andPsychotria kirkii Hiern. has been described for the first time at the ultrastructural level. Bacteria, resident in colleter-secreted mucilage in the space between calyx and corolla, invade stomatal pores which develop on the calyx protoderm. The bacteria proliferate in the substomatal cavity and then invade the calyx mesophyll. This invasion is most pronounced inP. punctata where the bacteria even penetrate and enter the cells of the vascular tissue. Although no sheath forms around the calyx nodules, the calyx mesophyll cells surrounded by the bacteria become identical in shape, size and secretory function to the invasive mesophyll cells of leaf nodules. The functional and evolutionary significance of calyx nodulation is discussed.
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  • 77
    ISSN: 1573-5036
    Keywords: Actinorhizae ; Datisca cannabina ; Frankia ; Nitrogen fixation ; Root nodules ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The fine structures of the microsymbiont inside the root nodules ofDatisca cannabina have been studied by light, by transmission- and by scanning-electron microscopy. The endophyte is prokaryotic and actinomycetal in nature. The hyphae are septate and branched, diameter 0.3–0.5 μm. The tips of hyphae are swollen to form electron-dense, clubshaped to filamentous vesicles, ranging in diameter: 0.4–1.4 μm. The endophyte penetrates through walls of the cortial cells. The infected zone is kidney shaped and confined to one side of the acentric stele. The orientation of infection is reversed from other actinorhizae exceptCoriaria. The hyphae are near the host cell wall and vesicles are directed towards the central vacuole. Vesicles are aseptate and no collapsing of the vesicle cell wall (void area) has been observed. Vesicle clusters structures are globular with an opening at one side of the cluster. The host cell is multinucleate or contains a lobed nucleus. Groups of mitochondria are located in between the hyphae, suggesting a strong association between the host and the endophyte for energy supply and amino acid production. The consequences of the inability to separate the mitochondria from the vesicle clusters in nodule homogenates in physiological studies have been discussed. Isolated vesicles clusters showed dehydrogenase activity, indicated by the presence of formazan crystals, after incubation with NADH and NBT. Strongest reducing activity was found within the vesicles. The possible role of filamentous vesicles in nitrogen fixation has been discussed.
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  • 78
    ISSN: 1573-5036
    Keywords: Alnus Hippophaë ; Mycorrhiza ; Myrica ; Nitrogenase ; Phosphate ; Triple symbiosis ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The roots ofHippophaë rhamnoides which regularly bear actinomycete induced nodules when growing on Scottish sand dunes have also been found to support an endomycorrhizal association withGlomus fasciculatus. Ultrastructural and cytochemical studies carried out on the indigenous infections of establishedHippophaë mycorrhizal roots would support the postulate that transport is indeed occurring between the fungal symbiont and the host plant and vice versa in respect of phosphate and carbohydrate. Experiments using various inoculation regimes, demonstrated the significant improvement in the mycorrhizal/nodulated plants compared to the nodulated-only and the mycorrhizal-only plants with respect to plant growth, uptake of phosphate and nitrogenase activity, when grown in a medium poor in combined nitrogen and soluble phosphate. Preliminary work onAlnus andMyrica species growing in Central Scotland indicates that the mycorrhizae associated with these nodulated root systems exhibit a different interaction pattern which may be dependent on habitat type and associated angiosperm species.
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  • 79
    ISSN: 1573-5036
    Keywords: Aeration status ; Microorganisms ; Mucilage ; Rhizosphere ; Ultrastructure ; Wheat root
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Outer layers of wheat roots grown in aerated and unaerated nutrient solutions were studied by transmission electron microscopy. Root growth was considerably impaired in unaerated nutrient solution. In contrast to aerated roots, no mucilaginous layer but dense bacterial colonization were observed on the root caps of unaerated roots. The root cap mucilage had apparently been decomposed by the microorganisms. The peripheral root cap cells of the unaerated roots appeared to contain less cell organelles than those of the aerated roots, while the central cap cells and the meristematic cells of the root tip seemed not to be affected by lack of aeration. The bacterial population in the elongation, root hair, and lateral root zones, was also remarkably higher on roots grown in unaerated nutrient solution. In the lateral root zone of unaerated roots, even the cortical cells were invaded by bacteria.
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  • 80
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    Cell & tissue research 225 (1982), S. 235-248 
    ISSN: 1432-0878
    Keywords: Rhinophore ; Larva ; Nudibranch ; Sensory cell ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The rhinophores of the veliger larva of Rostanga pulchra are located in the intravelar field near the base of the velar lobes. Each rhinophore is a cylindrical structure, tapering distally, and covered with a dense meshwork of microvilli. A conspicuous row of ciliary tufts runs along each side of the rhinophore and several stiffer tufts, composed of fewer cilia, are positioned around the tip or at the base. The rhinophoral epithelium consists of supporting cells, ciliated cells (giving rise to the ciliary rows), dendritic terminals (giving rise to the tufts around the apex), and sinuses containing occasional amebocytes. The lumen of the rhinophore is occupied by the rhinophoral ganglion and muscle cells that are oriented in two perpendicular planes. Cell bodies of the dendritic endings are located within the rhinophoral ganglion, which in turn joins into the optic and cerebral ganglia. Rhinophoral ganglionic neurons do not synapse with each other, but numerous neuromuscular synapses are found in the lumen of the rhinophore. Morphological evidence suggests that the dendritic endings are chemoreceptors and the ciliated cells are possibly mechanoreceptors but are not functional at this stage in development. The functional role of the rhinophores is discussed in relation to larval behavior at settlement and metamorphosis.
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    Cell & tissue research 226 (1982), S. 167-175 
    ISSN: 1432-0878
    Keywords: Pineal gland ; Ultrastructure ; Kangaroo rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ultrastructure of the pinealocytes of the wild-captured ord kangaroo rat (Dipodomys ordi) was examined. A homogeneous population of pinealocytes was present in the pineal gland of the kangaroo rat. The Golgi apparatus, granular endoplasmic reticulum, mitochondria, lysosomes, dense-core vesicles, vacuoles containing a flocculent material and lipid droplets were consistent components of the pinealocyte cytoplasm, whereas infrequently-observed organelles included centrioles, multivesicular bodies, subsurface cisternae, “synaptic” ribbons and cilia. The number of dense-core vesicles was relatively high and dense-core vesicles and vacuoles containing a flocculent material were present in the same cell. Although it has been recently suggested that two different secretory processes, i.e., neurosecretory-like (Golgi apparatus — dense-core vesicles) and ependymal-like (granular endoplasmic reticulum — vacuoles containing a flocculent material) may be involved in different regulatory mechanisms in the pinealocytes, the definitive answer to this is still far from clear. Therefore, the pineal gland of the kangaroo rat appears to be a good model for the study of the potential relationship between these two secretory processes, especially in respect to seasonal changes.
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  • 82
    ISSN: 1432-0878
    Keywords: Sperm polymorphism ; Ultrastructure ; Mollusca ; Prosobranchia
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    Topics: Biology , Medicine
    Notes: Summary The prosobranch Fusitriton oregonensis exhibits an unusual form of sperm polymorphism. The viable, eupyrene sperm are attached in groups of about fifty to worm-shaped, apyrene, carrier sperm. There is a second apyrene sperm, which is lancet-shaped and has a different internal organization than the carrier, but does not transport eupyrene sperm. The eupyrene sperm are filiform (185 μm long), with a conical acrosome, elongate nucleus and midpiece. They contain large stores of glycogen in the principal piece, together with an unusually high proportion of protein. The latter is due to a complex interconnecting system of fibres that supports the tail internally. A distinct annulus is located, characteristically, at the junction between midpiece and principal piece. The carrier sperm has a core of about 112 axonemes that arise from basal bodies in the anterior end and extend through its entire length of 36 μm. The basal bodies have unstriated rootlets that are embedded in a granular cap. Large membrane-bound “yolk bodies” are arranged along the length of the carrier sperm, on either side of the median axonemal core. Dense bodies, which may be indigestible residues formed from the degeneration of the nucleus, are excreted by exocytosis. Individual carrier sperm are capable of “corkscrew” propulsion, resembling that of spirochaetes. The lancet sperm is three times as long as the carrier. The sixteen or so axonemes, which are arranged peripherally like a cage enclosing the cytoplasm, originate from a dense centriolar plate in the anterior end. The cytoplasm is filled with secretions including small yolk granules, dense bodies (also excreted), clear vesicles, and a membranated granular secretion that resembles mucus. The possible functions of the lancet and carrier sperm are discussed.
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    Cell & tissue research 227 (1982), S. 429-437 
    ISSN: 1432-0878
    Keywords: Smooth muscle ; Arteriole ; Three-dimension ; Ultrastructure ; Laboratory rodents
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Three-dimensional aspects of smooth muscle cells of the microvas-culature were studied ultrastructurally in laboratory rodents by means of serial thin sections and reconstruction of muscle cell models. It was demonstrated that a muscle cell of an arteriole (luminal diameter (LD) 17 μm) in hamster striated muscle was spindle-shaped, 70 μm long, and wound twice round the vessel axis. The volume of the cell was calculated as 750 μm3 and its surface area as 1330 μm2. A muscle cell in an arteriole (LD 6 μm) in the rat retina was irregular in shape, about 22 μm long, and had branched processes. The cell volume was calculated as 139 μm3 and its surface area as 298 μm2.
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    Cell & tissue research 222 (1982), S. 41-51 
    ISSN: 1432-0878
    Keywords: Ultrastructure ; Interstitial cell ; Myenteric plexus ; Colon ; Rabbit
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The interstitial cells associated with the myenteric plexus of the rabbit colon were studied by scanning and transmission electron microscopy. It was demonstrated that the interstitial cells were stellate or fusiform in shape and located over the ganglia, over nerve bundles and between muscle cells. They were characterized by many slender processes, and resemble fibroblasts. No basal lamina was observed between the interstitial cells and muscle cells. It was concluded that structural features of the interstitial cells are distinctly different from those of neurons, Schwann cells, or of smooth muscle cells, while they show clear similarities to those of fibroblasts. By scanning electron microscopy the shapes and the relations of these cells could be demonstrated in great detail.
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    Cell & tissue research 222 (1982), S. 359-378 
    ISSN: 1432-0878
    Keywords: Axon terminals ; Substantia gelatinosa ; Spinal cord ; Noradrenaline ; Ultrastructure ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The noradrenergic terminals in the substantia gelatinosa of the dorsal horn of the cervical spinal cord of the rat were investigated by means of the histofluorescence technique and electron-microscopic cytochemistry using the glyoxylic acid-KMnO4 fixation technique. In accordance with the topographical distribution of fluorescent catecholaminergic fibers, noradrenergic terminals containing small granular vesicles were frequently observed electron microscopically in the outer layer of the substantia gelatinosa. These terminals were most frequently found to appose without showing typical synaptic features, small-caliber dendrites, spine apparatus, and rarely, large caliber dendrites. Only in a few cases, the noradrenergic terminals exhibited typical synaptic contacts with dendritic elements of small size. In addition, noradrenergic terminals apposed non-noradrenergic terminals containing small agranular vesicles. In rats bearing surgical lesions of the dorsal roots, no noradrenergic terminal were found in contact with the degenerated axon terminals in the substantia gelatinosa. These findings suggest that the noradrenergic afferents to the substantia gelatinosa may exert their influence on sensory transmission via dorsal horn cells.
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    Cell & tissue research 222 (1982), S. 695-698 
    ISSN: 1432-0878
    Keywords: Pineal gland ; Ultrastructure ; Dense-core vesicles ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Dense-core vesicles, 90–200 nm in diameter, were found in pinealocytes of the cat. They were present both in perikarya and cell processes.
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  • 87
    ISSN: 1432-0878
    Keywords: Immunoelectron microscopy ; Preoptic nucleus ; Goldfish ; Magnocellular neuroendocrine cells ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary We describe the ultrastructural localization of isotocin, vasotocin and neurophysin in the magnocellular preoptic nucleus of the goldfish. With the aid of immunocytochemical techniques, we see staining both in classical neurosecretory granules and in diffuse agranular form throughout somata and processes. Signs of cellular and synaptic interactions between chemically identified neurons include axon terminals which contain vasotocin immunoreactivity and membrane specializations (puncta adhaerentia) between adjacent somata. Our investigations provide an anatomical basis for neuroendocrine and neurotransmitter-like functions of peptidergic neurons in the teleost preoptic nucleus.
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    Cell & tissue research 224 (1982), S. 195-206 
    ISSN: 1432-0878
    Keywords: Pinealocytes ; Nucleolus ; Rat ; Ultrastructure ; Twenty-four-hour changes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary An ultrastructural and morphometric analysis was made of the nucleolar components in pinealocytes of 40 male Fischer rats sampled at eight times in an LD 12∶12 photoperiod cycle. Comparisons of results from the eight times showed variation in estimated mean volume of the granular component of ±29%, and of the fibrillar component ±11%, in relation to daily means. Peaks in mean volume of total nucleolus and its granular component occurred at 1 h of light. Near maximal and minimal mean volumes of the fibrillar component both occurred during both light and dark. Fibrillar centers (nucleolar organizer regions) of different sizes were found at all sampling times. It is concluded that temporal patterns in 24-h changes in the nucleolar components are most prominent in the granular component, and are more complex than suggested by changes in total nucleolar size or mean dimensions, and than represented by a simple biphasic circadian rhythm. Examples of different stages in the migration of the granular component, and of possible sites of nucleo-cytoplasmic transfer of nucleolar material, are described.
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  • 89
    ISSN: 1432-0878
    Keywords: GALT (gut-associated lymphoid tissue) ; Urodeles ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Résumé L'ultrastructure du tissu lymphoïde associé au tube digestif (GALT) a été étudiée chez l'amphibien urodèle, Pleurodeles waltlii. Les follicules lymphoïdes se présentent comme de vrais infiltrés entre les éléments conjonctifs de la muqueuse. Ils se trouvent principalement constitués par des plasmocytes mûrs et en développement, des macrophages et des granulocytes. Les cellules lymphoïdes migratrices provoquent une invasion massive de l'épithelium intestinal qui présente des modifications notables comme la disparition de la membrane basale et une diminution du nombre de cellules muqueuses. D'après son organisation et ses composants cellulaires, le GALT de P. waltlii semble représenter un précurseur phylogénétique primitif de la “barrière immunologique intestinale” des mammifères.
    Notes: Summary The ultrastructure of gut-associated lymphoid tissue (GALT) has been studied in the salamander, Pleurodeles waltlii. Lymphoid accumulations appear as true infiltrates scattered throughout the lamina propria cell elements. The most important components of these infiltrates are small and medium sized lymphocytes, and, in lesser amounts, developing and mature plasma cells, macrophages and granulocytes. Migrating lymphoid cells massively invade the intestinal epithelium inducing noticeable modifications, such as the disappearance of the basement membrane and decreased numbers of mucous cells. Thus, in its organization and cell composition, the GALT of P. waltlii appears to represent a primitive phylogenetic precursor of the mammalian “intestinalimmunologic ” barrier.
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    Cell & tissue research 225 (1982), S. 111-127 
    ISSN: 1432-0878
    Keywords: Loops of Henle ; Thin limbs ; Kidney (hamster) ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In the kidney of the Syrian hamster the descending thin limbs of both the short and long loops of Henle are not spatially separated from each other and descend between the vascular bundles. Ultrastructurally, five different epithelial types are distinguished in the thin limbs of the short and long loops of Henle. Short loops possess only a descending thin limb with a simply organized epithelium (type 1). Long loops comprise an upper and a lower part of the descending thin limb and the ascending thin limb. The upper part of the long descending thin limb is equipped with a complex and highly interdigitating epithelium with shallow junctions (type 2), which gradually transforms into the simple noninterdigitating type-3 epithelium of the lower part. In a minor portion of long descending thin limbs, however, the upper part begins with an even more complexly organized epithelium (type 2a) than type 2. Type-2a epithelium is conspicuously thicker and possesses a more elaborate mode of cellular interdigitation. Along the descent of this tubular part through the inner stripe of the outer medulla, type-2a epithelium transforms into type-2 epithelium. It is suggested that the long descending thin limbs, which start with type-2a epithelium, belong to the longest loops. The type-4 epithelium of the ascending thin limbs is characterized by flat and extensively interdigitating cells with shallow junctions. The unique pattern of the type-2 a epithelium favors the assumption that solute secretion essentially contributes to the increase in concentration of tubular fluid in long descending thin limbs.
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  • 91
    ISSN: 1432-0878
    Keywords: Opiate peptides ; Pituitary ; Pro-opiomelanocortin cells ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The effects of acute injections of synthetic opiate peptides into the lateral cerebral ventricle of young adult male rats on cells of the intermediate lobe of the pituitary were studied. Met-enkephalin (100/μg) injected into anesthetized rats, or 20 μg beta-endorphin administered via a previously implanted cannula to unanesthetized animals, will lead to cell degranulation and often to expanded Golgi zones and prominent regions of rough endoplasmic reticulum in secretory cells when tissue is fixed 45–60 min after peptide administration. Treatment of animals with the opiate antagonist naloxone hydrochloride prior to enkephalin injection appeared to prevent the cellular changes elicited with peptide alone. Observations suggest that opiate peptides administered to the cerebrospinal fluid may stimulate release of pro-opiomelanocortin-peptide from pituitary cells.
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    Cell & tissue research 226 (1982), S. 493-510 
    ISSN: 1432-0878
    Keywords: Ovarian cords ; Surface epithelium ; Fetal germ cells ; Mesonephros ; Ultrastructure ; SEM
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ovarian surface and associated germ cells have been studied in human fetuses from 12 weeks of age until near term, using light, TEM and SEM techniques. The surface epithelium and related cords proliferate extensively, especially at midterm. The cords in the ovarian cortex appear to be linked with ingrowths from the surface epithelium, and both structures have a common basal lamina. Germ cells are always interspersed among the somatic cells of the surface epithelium and associated cords. These results indicate that both the proliferating cords and surface epithelium may contribute to the formation of early follicles. Furthermore, the occurrence, of elements having some of the features of primitive steroidogenic cells in the regions of cordsurface epithelium continuity, suggests that both structures (surface epithelium and cords) contribute somatic cells, which in addition to becoming granulosa cells, might also contribute to the provision of primitive interstitial cells. Gonocytes tend to migrate through the developing ovarian tissue towards the surface where they become extruded into the peritoneal cavity. This phenomenon might contribute to the reduction in the number of germ cells at birth and parallels the atretic processes within the ovary.
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    Cell & tissue research 226 (1982), S. 541-554 
    ISSN: 1432-0878
    Keywords: Oral epithelium ; Cell differentiation ; Vitamin A ; Ultrastructure ; Stereology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ultrastructural changes induced by the topical application of retinol acetate on hamster cheek pouch epithelium were evaluated using stereological analysis. Electron micrographs were prepared of the basal and superficial regions of the nucleated cell layer of the epithelium obtained from 3 treated and 3 control animals and examined at two levels of magnification. A total of 528 micrographs were analyzed using a coherent double lattice test system. Although the mean thickness of the nucleated cell layer did not change significantly after 10 days of treatment with retinol acetate the formation of keratinized squames was completely inhibited. This was paralleled by significant changes in the volume density of a number of organelles in both the basal and superficial strata. Rough endoplasmic reticulum increased significantly whereas filaments, which maintained a constant diameter of approximately 9 nm, keratohyalin granules and membrane-coating granules decreased in both strata. Desmosomes also showed a significant decrease in numerical area density in the treated tissues. In contrast, no changes were observed in the volume density of the Golgi apparatus, free ribosomes or mitochondria in the treated epithelium. It is concluded that this treatment provides an epithelium lacking all features of keratinization and may be a useful model for examining metabolic activities specifically associated with keratinization.
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  • 94
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    Cell & tissue research 226 (1982), S. 565-578 
    ISSN: 1432-0878
    Keywords: Mechanosensory hair ; Chordotonal organ ; Ultrastructure ; Crustacea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In this study we examine the fine structure of mechanosensory hairs in the antennule of crayfish. The sensory hair is a stiff shaft with feather-like filaments. The hair's base is a large expansion of membrane which allows the hair shaft to deflect. The sensory transducing elements are located far from the hair, but are coupled mechanically with the hair shaft by a fine extracellular chorda. The sensory element is a type of scolopidium which consists of a scolopale cell and three sensory cells with a 9 + 0 type ciliary process. This type of scolopidium is characteristic of the chordotonal organ that has no cuticular structure on the surface of the exoskeleton. In this crustacean hair receptor, the deflection of the cuticular hair is transmitted through the chorda to the scolopidium which is a tension-sensitive transducer. The present study reveals that the mechanosensory hair of decapod crustaceans is a chordotonal organ accompanied by a cuticular hair structure. We also discuss comparative aspects of cuticular and subcuticular chordotonal organs in arthropods.
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    Cell & tissue research 227 (1982), S. 129-137 
    ISSN: 1432-0878
    Keywords: Mitochondria ; Ultrastructure ; Microinjection ; ATP ; ADP ; Amoeba proteus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Microinjection of adenine nucleotides and substrates into the cytoplasm of Amoeba proteus followed by EM examination has been used in an attempt to relate alterations in mitochondrial morphology with functional changes. Contracted mitochondria with dark matrix and wide cristae (Type I), and expanded mitochondria with light matrix and narrower cristae (Type II) coexist in normal active amoebae, but their numbers can be varied according to different cell activity states. Following injection of ATP, the mitochondria of the amoebae showed a time-dependent movement towards a predominately Type II form, whilst injections of ADP produced predominately the Type I form. Injection of succinate or deionised water, even in large amounts, had little effect on the numbers of Type I or Type II forms. The change induced by ATP was of long duration; that induced by ADP was influenced by both concentration injected and the cell's substrate levels. With 3 mM solutions of ADP the mitochondrial population was primarily of Type I organelles; higher ADP concentrations or the simultaneous injection of succinate, however, resulted in a switch with time to increased proportions of Type II mitochondria. The results extend the findings of previous in vivo and in vitro mitochondrial studies and are discussed in the light of these.
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  • 96
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    Cell & tissue research 227 (1982), S. 139-151 
    ISSN: 1432-0878
    Keywords: Migration ; Primordial germ cell ; Teleost ; Oryzias latipes ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The primordial germ cells (PGCs) of Oryzias latipes in migration to the gonadal anlage have been investigated by light and electron microscopy. The ultrastructure of the PGCs, which occur in the subendodermal space on the syncytial periblast, differ conspicuously from that of the surrounding endodermal cells. After the PGCs move to the cavity between lateral plate and ectoderm, they are taken into the somatomesodermal layer and transferred to the dorsal mesentery where they form gonadal anlage with mesodermal cells. During their translocation to the dorsal mesentery through the somatic mesoderm, apparently without formation of pseudopods, the PGCs are completely surrounded by mesodermal cells. Since these conditions seem unfavorable to the active translocation of the PGCs to the dorsal mesentery, it is more likely that the PGCs are transferred passively by the morphogenic activity of the lateral-plate mesoderm. Counts of the number of the PGCs revealed that they are mitotically dormant during the migratory period. After the completion of the migration, they regain their proliferative activity. The PGCs in the female proliferate more actively than those in the male, which provides the first morphological indication of sex differentiation in this species of fish.
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  • 97
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    Cell & tissue research 227 (1982), S. 201-211 
    ISSN: 1432-0878
    Keywords: Optic systems ; Axonal growth ; Myelination ; Ultrastructure ; Teleosts
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The early differentiation of the optic pathway of the trout was studied by means of autoradiography, silver impregnation and electron microscopy. Ingrowth of optic nerve fibers into the optic tectum was consistently shown by tracer application and Golgi studies to occur at stage 28, about one week before hatching. Fibers being arranged in discrete bundles were rapidly growing through the longitudinal axis of tectum and at stage 33 reached its posterior end. Cross sections of these fiber bundles at different positions revealed myelin ensheatment to be initiated at the end of stage 34 at the anterior pole of the tectum. Since in the optic nerve of the trout the onset of myelination occurred even earlier (stage 33), it is assumed that this differentiation process follows a rostro-caudal gradient during development of the optic pathway.
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  • 98
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    Cell & tissue research 227 (1982), S. 371-386 
    ISSN: 1432-0878
    Keywords: Tentacle sensory input system ; Neuroendocrine control of growth ; Ultrastructure ; L. stagnalis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Several environmental factors influence the growth of the basommatophoran freshwater snail Lymnaea stagnalis. Growth is hormonally controlled by 4 cerebral clusters of ca 50–75 peptidergic, neuroendocrine Light Green Cells (LGC). The present light, transmission, and scanning electron microscopic study shows that the LGC are synaptically contacted by a tentacle sensory system (TSS). The TSS consists of 2 types of primary sensory neurone, viz. ca 150 S1-cells and ca 50–100 S2-cells. A S1-cell has a non-ciliated dendrite and an axon branch that synaptically contacts the soma of a S2-cell. A S2-cell has a branching, ciliated dendrite. Probably, S1- and S2-cells have different sensory modalities and can integrate sensory information by intersensory interaction. The S2-axons run through the tentacular nerves, the cerebral ganglia, and the intercerebral commissure. In each ganglion S2-axons branch and form synaptic contacts on the axons and somata of the LGC and on glial cells that surround the LGC. In an LGC-cluster, 1–3 LGC-somata are particularly strongly innervated. Probably, the TSS is involved in the environmental control of growth in L. stagnalis.
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  • 99
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    Cell & tissue research 221 (1982), S. 551-581 
    ISSN: 1432-0878
    Keywords: Non-adrenergic, non-cholinergic nerves ; Cholinergic nerves ; Ultrastructure ; Nervous transmission
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In order to test the premise that non-adrenergic, non-cholinergic (NANC) autonomic nerves have a distinctive ultrastructural appearance, clearly different from that of cholinergic nerves, a detailed quantitative ultrastructural analysis has been made of the non-adrenergic innervation of 15 tissues thought from pharmacological evidence to be innervated by NANC nerves (rat and rabbit anococcygeus muscles; rabbit hepatic portal vein; extrinsically denervated toad lung); cholinergic nerves (atria of rat, rabbit, guinea-pig and toad); or both (guinea-pig cervical and thoracic trachealis muscle; rabbit rectococcygeus muscle; urinary bladder of rat, rabbit, guinea-pig and toad) in addition to their adrenergic supply. Following fixation with a modified chromaffin procedure allowing identification of adrenergic nerves, large, randomly selected samples of non-adrenergic nerve profiles from each tissue were analysed with respect to numbers, relative proportions, and size frequency distributions of different vesicle classes within the profiles. The neuromuscular relationships within each tissue were also analysed. On the basis of these analyses, it is clear that there are no consistent ultrastructural differences between cholinergic and NANC autonomic nerves: neither proportions nor sizes of the vesicles provide any clue as to the transmitter used by a particular nerve. The great majority of nerve profiles, whether cholinergic or NANC, contain predominantly small clear “synaptic” vesicles. Large filled “peptidergic” vesicles are no more common in most NANC nerves than in most cholinergic ones. It is concluded, on ultrastructural grounds, that the primary transmitter in these NANC autonomie nerves is most likely to be stored in and released from the small clear vesicles.
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    Cell & tissue research 221 (1982), S. 607-615 
    ISSN: 1432-0878
    Keywords: Hemocytes ; Drosophila ; Ultrastructure ; Phagocytosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Hemocytes of Drosophila melanogaster and Drosophila yakuba larvae have been defined in terms of their ultrastructure and functions in “coagulation”, wound healing, encapsulation, phenol-oxydase activity, and phagocytosis. The position of these cells among the classical hemocyte types of insects is determined. We distinguish two plasmatocyte types (macrophage plasmatocytes and lamellocytes) which do not seem to belong to the same lineage, and oenocytoids which are the crystal cells of the literature.
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