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  • Springer  (11)
  • American Meteorological Society
  • 1980-1984  (6)
  • 1970-1974  (5)
  • 1950-1954
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  • Springer  (11)
  • American Meteorological Society
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  • 1
    ISSN: 1615-6102
    Keywords: Wall ingrowths ; Development ; Leaf ; Zostera capensis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The development of wall ingrowths in leaf blade epidermal cells of the marine angiospermZostera capensis was studied by electron microscopy. Prior to the appearance of ingrowths long profiles of endoplasmic reticulum cisternae become arranged peripherally closely following the contours of the walls. The plasmalemma assumes a wavy appearance and in regions where wall ingrowths first start forming (i.e., along the radial, inner tangential and transverse walls) the plasmalemma becomes separated from the walls by an undulating extracytoplasmic space. Small, irregular projections of secondary wall material make their appearance here. Paramural bodies, dictyosomes, endoplasmic reticulum (ER) and possibly also microtubules seem to be closely associated with the initiation and subsequent development of wall projections. As the cells mature, new ingrowths arise in a centrifugal direction along the radial and transverse walls. When wall ingrowths reach a certain stage of their development, mitochondria become strongly polarized towards them and become closely associated with the plasmalemma which ensheaths the ingrowths. There is often also a close association between ER cisternae and the involuted plasmalemma of the wall projections. Initially ingrowths are slender, curved structures, but become more complex as the cells mature. Ingrowths are most extensively developed along the inner tangential and transverse walls. As epidermal cells age there is a loss of wall material from the ingrowths. The probable significance of the formation of wall ingrowths in the epidermal cells is also discussed.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 9 (1972), S. 122-130 
    ISSN: 1432-0827
    Keywords: Tetracycline ; Development ; Calcification ; Statolith ; Nematocysts ; Aurelia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé L'effet de la tétracycline HCl sur la synthèse de statolithes de sulfate de calcium chezAurelia a été étudié. La tétracycline inhibe la synthèse de statolithes et nématocystes à un stade précoce de strobilation. La tétracycline, cependant, n'est pas incorporée dans les statolithes ou nématocystes en formation. Comme la tétracycline ne se combine pas avec le calcium des statolithes de sulfate de calcium dihydraté d'Aurelia, l'explication des effets d'inhibition sur la différenciation de statolithes et nématocystes ne semble pas liée avec un facteur en rapport avec l'incorporation. Des étudesin vitro de quatre systèmes inorganiques de calcium et de tétracycline montrent que le sulfate de calcium dihydraté (gypse) n'incorpore pas la tétracycline: il en est de même de son équivalent isostructural, le phosphate de calcium hydrogéné dihydraté (brushite). Le carbonate de calcium et le phosphate de calcium (apatite) incorpore la tétracycline. L'explication des différences de comportement du calcium peut être liée à la structure cristalline des composés respectifs, et, en particulier, au fait que l'ion Ca est prêt ou non à réagir avec la tétracycline.
    Abstract: Zusammenfassung Es wird über die Wirkung von Tetracyclinchlorhydrat auf die Synthese von Calciumsulfat-Statolithen beiAurelia berichtet. Wird das Tetracyclin in einem Frühstadium der Strobilation verabreicht, so hemmt es die Synthese der Statolithen und der Nematocysten. Das Tetracyclin wird jedoch nicht in die sich bildenden Statolithen oder Nematocysten eingebaut. Da sich das Tetracyclin nicht mit dem Calcium der Calciumsulfatdihydrat-Statolithen derAurelia verbindet, so kann dessen Hemmwirkung auf die Statolithen und die sich differenzierenden Nematocysten offenbar nicht mit einem einbaubedingten Faktor erklärt werden. Untersuchunge, die in vitro mit vier verschiedenen anorganischen Calciumsalzen und Tetracyclin ausgeführt wurden, zeigten, daß weder Calciumsulfatdihydrat (Gips), noch dessen isotrukturelles Aequivalent Calciumhydrogenphosphatdihydrat (Bruschit) Tetracyclin einbauen. Dagegen inkorporieren Calciumcarbonat und Calciumphosphat (Apatit) das Tetracyclin. Die Erklärung für dieses unterschiedliche Verhalten der Calciumsalze findet sich in der Kristallstruktur der betreffenden Verbindungen, d.h. es hängt davon ab, ob das Calciumion ür die Reaktion mit Tetracyclin leicht verfügbar ist.
    Notes: Abstract The effect of tetracycline HCl on synthesis of calcium sulphate statoliths inAurelia is reported. Tetracycline inhibits synthesis of statoliths and nematocysts when administered at an early stage of strobilation. The tetracycline, however, is not incorporated into the developing statoliths or nematocysts. As the tetracycline does not combine with the calcium of the calcium sulfate dihydrate statoliths ofAurelia, an explanation for its inhibitory effects on statoliths and nematocyst differentiation apparently does not rest with an incorporation-related factor. In vitro studies of four inorganic calcium systems and tetracycline revealed that calcium sulfate dihydrate (gypsum) did not incorporate tetracycline nor did its isostructural equivalent, calcium hydrogen phosphate dihydrate (brushite). Calcium carbonate and calcium phosphate (apatite) did incorporate tetracycline. The explanation for these different behaviors of calcium can be found in the crystal structure of the respective compounds, namely, whether or not the Ca ion is readily available to react with tetracycline.
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 140 (1973), S. 203-216 
    ISSN: 1432-0878
    Keywords: Synapses ; Development ; Chick embryo ; Cell culture ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The formation and development of synaptic contacts between dissociated chick spinal cord neurons has been investigated. By the 6th day in vitro “immature” profiles with few vesicles were observed. By 14–18 days “mature” types with numerous vesicles were found, indistinguishable from those of newly hatched chick spinal cord. After this period degeneration occurred, and was especially marked in the post-synaptic element. Such degeneration could be postponed by the addition of small numbers of somatic muscle cells. The Kanaseki and Kadota (1969) technique was applied to the study of coated vesicles at various stages of synaptic development.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 208 (1980), S. 171-181 
    ISSN: 1432-0878
    Keywords: Microtubules ; Dendritic spine apparatus ; Synapse ; Development ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Using techniques for enhanced microtubular preservation, including albumin pretreatment (Gray, 1975), occipital cortex of rats was studied electron microscopically at various ages of development. A close structural relationship was seen between microtubules, sacs of SER and the postsynaptic “thickening” in primordial spines and with the dense “plate” material of spine apparatuses. Stereoscopic preparations in addition show a more complicated substructure than previously described for the “plate”. Microtubules may contribute to the formation of the “plate” of the spine apparatus which in turn is associated with the postsynaptic “thickening” of the mature spine. Possible functional correlates are discussed.
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  • 5
    ISSN: 1432-0878
    Keywords: Pars tuberalis ; Rat ; Development ; Secretion ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The development of the pars tuberalis was studied in the rat fetus from 13 days of gestation to 6 weeks after birth. After the closure of Rathke's pouch, the pars tuberalis anlage is clearly distinguishable from the anlagen of the partes intermedia and distalis. It comprises the entire basal portion of the adenohypophysial anlage; the limit between the anlagen of the pars tuberalis and the pars distalis is defined by Atwell's recess, i.e. the pathway taken by the hypophysial vessels coming from the vascular plexus of the median eminence. At 14 days the pars tuberalis cells are characterized by the presence of glycogen which persists in the adult. Their secretory differentiation (elaboration of granules with a diameter of 100–120 nm) is obvious at 15 days of gestation. It therefore, clearly precedes that of the other hypophysial cell types. Its functional differentiation takes place well before its adhesion to the primary vascular plexus of the portal system. Cystic formations appear just before birth in the pars tuberalis, much later than those of the pars distalis. These observations on the development of the pars tuberalis, together with previous observations on the adult PT in various species, showing that the specific glandular cells of the pars tuberalis are cytologically different from all known adenohypophysial cell types, seem to indicate a specific endocrine function of this lobe.
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  • 6
    ISSN: 1432-0878
    Keywords: Synaptic vesicles ; Development ; Golgi apparatus ; Smooth endoplasmic reticulum ; Zinc iodide-osmium technique
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Routine electron microscopy and a zinc iodide-osmium tetroxide technique (ZIO), recently found to be specific for synaptic vesicles, were used to study the origin of synaptic vesicles during postnatal development in the lumbosacral enlargement of the albino rat. In immature nervous tissue, a large number of vesicles, indistinguishable from synaptic vesicles (S vesicles), were found in the Golgi apparatus and in different portions of the axon where they were often intermingled with elements of the smooth endoplasmic reticulum (SER). Ten to twenty percent of these S vesicles within the Golgi apparatus as well as the majority of these vesicles in all parts of the axon were positive to ZIO. Much of the SER in axons was also positive. The number of vesicles and elements of the SER showed some decrease in the non-terminal portion of axons on day 21 and even more of a decrease in adult neurons. These data suggest that synaptic vesicles are produced in the Golgi apparatus and SER in immature neurons. The decrease in S vesicles and SER in adult neurons suggests a drop in synaptic vesicle production after synaptogenesis has ended. In addition, the material that has been studied shows that ZIO staining is not limited to synaptic vesicles during development since oligodendroglia and endothelial cells are also stained during this period.
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    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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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 231 (1983), S. 93-102 
    ISSN: 1432-0878
    Keywords: Synapses ; Microtubules ; Presynaptic dense projections ; Development
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Using techniques for enhanced microtubular preservation (albumin pretreatment of Gray) occipital and pyriform cortices of rats were studied by electron microscopy at various stages of development. A close structural relationship was seen between microtubules (mts), focal membrane densities, synaptic vesicles, and presynaptic dense projections (pre-dps) during maturation. Mts were seen in the neonates to be focused onto the inner surface of immature axonic profiles merging or sometimes fragmenting there. Focal densities occur at these attachment sites and thereafter synaptic vesicles clothe the mts and abut onto these presumed primordial pre-dps. Thus, mts may contribute to the initial formation of pre-dps as well as their maintenance in the adult and may act to channel the first synaptic vesicles to the site of eventual synaptic contact and transmitter release.
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  • 9
    ISSN: 1432-0878
    Keywords: Sea star ; Development ; Cuticle ; Extracellular materials ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The fine structure of conspicuous extracellular materials during the life history of a sea star (Patiria miniata) is described. The outer surface of the developing sea star is covered by two morphologically different cuticles that appear sequentially during ontogeny. The primary cuticle, which is about 120 nm thick and two-layered, is present from mid-blastula through the end of the larval stage. The secondary cuticle, which is about 1 μm thick and three-layered, first appears on the epidermis of the rudiment region of the larva and, after metamorphosis, covers the entire epidermis of the juvenile and adult stages. During ontogeny, there are only two conspicuous gut cuticles: the first lines the newly invaginated archenteron at the start of the gastrula stage, and the second lines the esophagus during the larval stage. A blastocoelic basal lamina first appears at mid-blastula and persists as subectodermal and subendodermal basal laminae. Ruthenium red-positive granules are detectable between the lateral surfaces of adjacent ectodermal cells during part of the gastrula stage; this transient intercellular material may possibly aid in lateral adhesion between cells.
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 229 (1983), S. 145-154 
    ISSN: 1432-0878
    Keywords: Pluteus ; Nervous system ; Development ; Larva ; Echinoidea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Transformation of the gastrula to the pluteus includes development of the ability of the larva to control the direction of ciliary beat and coordinate activities of the ciliary band with activities of the esophageal muscles (48–60 h, 15°C). Glyoxylic acid-induced fluorescence shows several cells of the animal plate to contain catecholamines in the 36-h gastrula. As the ectoderm thickens to form the ciliary band (36–48 h), the catecholamine-containing cells increase in number and occur dispersed throughout the band. Tissues with the ultrastructural characteristics of nerves first become apparent associated with the ciliary band in 60-h larvae. The coincident development of coordinated behaviour and the appearance of cells with ultrastructural and histochemical characteristics of nerves suggests that the larval nervous system is derived at least in part from cells of the animal plate and develops in association with the ciliary bands.
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