ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • Electron microscopy  (107)
  • Springer  (107)
  • Cambridge University Press
  • Nature Publishing Group
  • 1980-1984  (59)
  • 1975-1979  (48)
  • 1984  (21)
  • 1981  (38)
  • 1979  (48)
Collection
Publisher
  • Springer  (107)
  • Cambridge University Press
  • Nature Publishing Group
  • Wiley-Blackwell  (5)
Years
  • 1980-1984  (59)
  • 1975-1979  (48)
Year
  • 1
    ISSN: 1432-0827
    Keywords: Parathyroid hormone ; Osteoclasts ; Electron microscopy ; Morphometry ; Metaphysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The effects of parathyroid hormone (PTH) on the size of the osteoclasts, nuclei, ruffled borders, and clear zones in long bones of thyroparathyroidectomized (TPTX) rats were quantitated as a function of time. These data were compared with the number of osteoclasts in the bone and with plasma calcium levels. A significant increase in the average size of the ruffled borders was demonstrated 30 min after injection of 50 U of purified bovine PTH, and of the clear zones 30–90 min after PTH. This was followed at 90 min by an increase in the average size of the cells. The sizes of ruffled borders and clear zones dropped sharply to control levels after 6 h, whereas the size of the cells remained elevated up to 12 h and returned to control values at 24 h. Plasma calcium levels were increased, but not significantly, between 30 min and 6 h. An increase in the number of osteoclasts was significant after 12 h. Removal of the parathyroid glands did not diminish the normal activity of osteoclasts. In animals with intact glands injection of 50 U of PTH did not cause a significant change in cell size or resorbing apparatus. It is concluded that PTH acts to rapidly stimulate the bone resorptive activity of osteoclasts and to cause a delayed increase in their number.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 33 (1981), S. 143-151 
    ISSN: 1432-0827
    Keywords: Calcium transport ; Cytochalasin B ; Dihydrocytochalasin B ; Colchicine ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary In vivo calcium absorption was studied in normal and rachitic chicks. Cytochalasin B (CB) at a concentration of 25 µg/ml added to the medium inside the duodenal lumen inhibited calcium absorption (20 min) from 82.5±1.9% of calcium absorbed in the controls to 59.2±3% in normal and from 70.0±2.3% to 47.0±2.1% in rachitic chicks. In vitro studies by everted ileal sacs of young rabbits also showed an inhibition of active transport of calcium due to CB. Whereas in the controls the ratio of45Ca concentrations in serosal and mucosal media (60 min) was 7.2±0.32, the ratios were 5.24±0.52; 4.40±0.36; 3.40±0.42; 5.77±0.52; 1.38±0.08; and 1.06±0.02 in the presence of CB at concentrations of 5, 10 and 25 µg/ml; colchicine 10−4M, Na citrate 0.02M, and heat-devitalized conditions, respectively.45Ca concentration in the mucosal scrapings was also affected. It showed an increase from controls (15,101±404 cpm/mg) and correlated with CB concentration: 17,378±489, 19,015±1000, and 20,201±362 at 5, 10, and 25 µg/ml, respectively. Dihydrocytochalasin B also inhibited active calcium transport and caused an increase in45Ca concentration in the mucosal scrapings. Correlated electron microscopic studies showed certain changes in the brush border, especially in some actin microfilaments in the terminal web region. It seems that these morphological alterations may be related to transcytoplasmic movement of calcium.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 3
    ISSN: 1432-0827
    Keywords: Alcohol ; Electron microscopy ; Growth plate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary We have previously demonstrated that ethanol has a direct toxic effect on the rat skeleton characterized by decreased trabecular bone volume. In the present study, we examined the ultrastructure of the distal radial epiphyseal growth plates in these same animals. Eight weeks of ethanol administration to 12 male rats results in serum alcohol levels of 140 mg/dl but did not alter the width or light microscopic appearance of the radial growth plate. Quantitative electron microscopy failed to demonstrate morphologic evidence of toxicity in the skeletal cells. We conclude that although ethanol appears to have a direct effect on rat bone characterized by enhanced resorption, toxicity is not attended by ultrastructural changes in the skeletal cells.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 33 (1981), S. 529-540 
    ISSN: 1432-0827
    Keywords: Bone cells ; Electron microscopy ; PTH ; PGE1
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Four different cell populations—designated PF, OB, OC, and PC—were isolated from calvaria of 18-day-old chick embryos for analysis of the effects of hormones on bone tissue. The cell populations were studied with histological and biochemical methods. Apart from the well-known cell types present in calvaria, a new cell type was found in the noncalcified organic matrix between the osteoblastic layer and the calcified matrix. These cells were provisionally called osteocytic osteoblasts. They represent the “transition state” between osteoblasts and osteocytes. On the basis of histological studies with light microscopy (LM), transmission electron microscopy (TEM) and scanning electron microscopy (SEM), the PF population was considered to originate primarily from the periosteal fibroblasts, the OB population from the osteoblasts and osteocytic osteoblasts. The population of cells still present in calvaria after removal of periosteal fibroblasts and osteoblasts was called the OC population. This cell population was very much enriched with osteocytes. The fourth isolated population (PC) was a mixed population of fibroblasts, osteoblasts, and preosteoblasts. On exposure to parathyroid hormone (PTH), all four cell populations showed increased lactate production, but only the OB and OC populations displayed increased cAMP production. Prostaglandin E1 (PGE1) stimulated cAMP production in both OB and PF cells. From the results of this study it was concluded that PTH receptors are present on all of the cell types studied, but that occupancy of the receptor induces adenylate cyclase stimulation only in osteocytes and fully differentiated osteoblasts.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 29 (1979), S. 101-105 
    ISSN: 1432-0827
    Keywords: Osteon ; X-ray diffraction ; Pole figures ; Electron microscopy ; Calcification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The X-ray diffraction method based on pole figures has been applied to single osteon samples in order to obtain information about the texture of the inorganic bone fraction and the way it changes during calcification. The osteon samples were cylindrically shaped, with axes corresponding to those of the haversian canals. Selection was carried out according to the degree of calcification and the orientation of collagen bundles and inorganic particles. Osteons at both the initial and final stages of calcification were chosen. Arrangements of fiber bundles and inorganic particles in successive lamellae characteristic of three types of osteons were selected: longitudinal, alternate, and transversal. The results indicate that in all three types of osteons, the long axis of the sample is apparently the only direction of orientation because the transversally oriented crystallites give an isotropic diffuse scattering as would be expected if all the inorganic particles were irregularly oriented around the osteon axis. The number of longitudinally oriented crystallites increases progressively from transversally oriented osteons to alternately and longitudinally oriented ones. The crystallite orientation in an axial direction increases in fully calcified osteons. This last result is in agreement with the electron microscopic finding that the long needle-shaped crystallites covering much more than a major collagen period and measuring 40–45 Å in width increase in number as calcification proceeds.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 33 (1981), S. 119-124 
    ISSN: 1432-0827
    Keywords: Avian eggshell ; Microstructure ; Electron microscopy ; Electron diffraction ; Calcite growth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The eggshell of the domestic fowl has been studied by transmission electron microscopy and diffraction. Thin sections of shell were prepared by chemical and ion-beam thinning techniques. Each calcite column of the palisade layer consisted of crystallites of diameter 20 to 30 µm with some tendency for crystallite alignment within a single column. Evidence indicates that there was no significant preferred orientation in the palisade layer as a whole. Only in the surface layer was any preferred orientation detected, and here {1014} planes tended to lie parallel to the surface. The results are compared with previously published data, and calcite nucleation and growth are discussed.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 7
    Electronic Resource
    Electronic Resource
    Springer
    European biophysics journal 7 (1981), S. 209-212 
    ISSN: 1432-1017
    Keywords: Photosynthetic bacteria ; Electron microscopy ; Planar lattices
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract The thylakoids of Rhodopseudomonas viridis have been studied by freeze-fracturing whole cells. Depending on growth conditions and treatment before freezing, three different types of particle arrangements in the photosynthetic membrane are reported: a random arrangement, an isometric (quadratic) lattice arrangement with a lattice constant of 12.5 ± 0.8 nm, and a hexagonal lattice arrangement with a lattice constant of 12.5 ± 0.8 nm.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 8
    ISSN: 1432-072X
    Keywords: Acetobacter suboxydans ; Bacteriophage A-1 ; Restriction ; Modification ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A bacteriophage ofAcetobacter suboxydans was isolated and found to correspond to type A phage according to Bradley's classification. The phage contains double stranded DNA. The length of the latency period and burst size could not be precisely determined because of apparent non-synchronous release of phage from single infective cycles. The host range was determined using 24 strains ofAcetobacter andGluconobacter species. Evidence for a probable occurence of host determined restriction and modification was obtained withAcetobacter suboxydans strain ATCC 621. The phage is designated A-1 and it is the first one to be reported forAcetobacter.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Archives of microbiology 123 (1979), S. 101-103 
    ISSN: 1432-072X
    Keywords: Bdellovibrio ; Cyanobacteria ; Marine sponges ; Symbiosis ; Infection ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A bdellovibrio-like bacterium was observed infecting unicellular symbiotic cyanobacteria in two coral reef sponges, Neofibularia irata and Jaspis stellifera. The infecting bacterium, which was located between the cell wall and the cytoplasmic membrane of the cyanobacteria, was similar in size and appearance to previously described bdellovibrios. This observation is believed to extend the host range of the bdellovibrios.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Archives of microbiology 130 (1981), S. 125-128 
    ISSN: 1432-072X
    Keywords: Rhodospirillum rubrum ; Chromatophores ; Reaction centers ; Liposomes ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In freeze-fractures of chromatophores of Rhodospirillum rubrum the reaction centers are seen as hexagonal arranged particles of 13 nm diameter with a density of around 5,500 particles per μm2. Similar regions on the cytoplasmic membrane suggest that these parts are the prospective invagination sites. Isolated reaction centers are easily incorporated into liposomes. In freeze fractures of liposomes particles similar in shape and size, although less dense as in chromatophores are observed. In negative staining much smaller units of only 5 nm in diameter are found indicating that reaction centers occur in the membrane as tri- or tetramers. There is a strong correlation between particle density in chromatophores and titratable reaction centers remaining in these membranes after extraction of reaction centers by detergents; both values are in good agreement with the yield of reaction centers at a given detergent concentration.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 11
    ISSN: 1432-072X
    Keywords: Alcohol dehydrogenase ; Acetaldehyde dehydrogenase ; Clostridium kluyveri ; Electron microscopy ; Polygonal bodies ; Enzyme complex
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The alcohol-acetaldehyde dehydrogenase complex of Clostridium kluyveri has been separated from contaminating β-hydroxybutyryl-CoA dehydrogenase by repeated precipitation with manganese and ammonium sulfate. Mn++ was required for maximum alcohol dehydrogenase activity. The molecular weight of the enzyme complex was 194,000 as determined by sucrose density gradient centrifugation. The enzyme complex has been shown to contain two types of subunits with molecular weights of 55,000±2,600 and 42,000±1,200, respectively which are arranged in “H”-shaped particles. In solutions with an ionic strength above 25 mM the enzyme complex precipitated in the form of lumps as has been shown with specific ferritin-conjugated antibodies. These lumps are assumed to be aggregated polygonal bodies present in C. kluyveri.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 12
    Electronic Resource
    Electronic Resource
    Springer
    Archives of microbiology 129 (1981), S. 129-134 
    ISSN: 1432-072X
    Keywords: Cockroach ; Hindgut ; Distribution ; Microbial morphotypes ; Transmission ; Electron microscopy ; Statistical analysis ; Eublaberus posticus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The relative numbers of fourteen microbial morphotypes in transmission electron micrographs of the hindgut of a cockroach, Eublaberus posticus, were counted and their distribution was analyzed statistically. The microbiota of three wall-associated regions (the anterior paunch, the posterior paunch, and the black band region) was clearly different from that of the gut lumen. The three wall fractions were also significantly different from each other. Only one of the fourteen types, prosthecate bacteria, appeared to be distributed randomly in the four fractions. The five main wall-associated morphotypes individually constituted up to 41% of the microbes in some micrographs. They included one type with the characteristic morphology of Methanospirillum. Six morphotypes rarely made up over 2% of the population, but were consistently present. The numbers of the remaining three morphotypes were quite variable between micrographs and between individual insects, but when present often made up 5–10% of the population.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 13
    ISSN: 1432-072X
    Keywords: Biological control ; Cyanobacteria ; Electron microscopy ; Entrapment ; lysis ; Myxococcus ; Phormidium ; Spherule
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A Myxococcus xanthus isolate from a farm drainage ditch, designated strain PCO2, is capable of rapidly inducing lysis of both agar and liquid-grown cultures of the cyanobacterium, Phormidium luridum, var. olivacea. Microscopic studies of the predator-prey interaction demonstrate that lysis of the cyanobacterium occurs within clumps and spherules formed by the cells of M. xanthus PCO2. In the earliest stage, one sees the formation of irregular microclumps of bacteria and cyanobacterial filaments. As these clumps mature, colonies 1 to 6 mm in diameter develops. The center of these densely green colonies contains cyanohacteria in various stages of degradation, while the periphery is almost exclusively a tightly woven mass of myxobacterial cells. Electron microscopy shows that long extrusions from the outer membrane of the M. xanthus PCO2 cells are involved in the formation both of initial clumps and of mature colonial spherules. These extrusions appear to efficiently entangle the cyanobacterial filaments in the culture environment. Predator-to-prey ratios of 1/10, 1/100 and 1/1,000 have resulted in cyanobacterial lysis. Because the entrapment and lysis of P. luridum filaments by M. xanthus PCO2 appears to be independent of any other heterotrophic nutritional requirement, as well as of environmental agitation, this system has potential as a biological control technique for undesirable aquatic cyanobacteria.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 14
    Electronic Resource
    Electronic Resource
    Springer
    Archives of microbiology 138 (1984), S. 273-277 
    ISSN: 1432-072X
    Keywords: Cyanobacteria ; Secondary metabolite ; Allelopathy ; Photosynthesis ; Electron transport ; Thylakoids ; Herbicides ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Cyanobacterin is a secondary metabolite produced by the cyanobacterium, Scytonema hofmanni. Highly purified cyanobacterin was found to inhibit the growth of many cyanobacteria at a minimum effective dose of 2 μg/ml (4.6 μM). The antibiotic had no effect on eubacteria including the photosynthetic Rhodospirillum rubrum. The site of action of cyanobacterin was further investigated in the unicellular cyanobacterium, Synechococcus sp. Electron micrographs of antibiotic-treated Synechococcus cells indicated that cyanobacterin affects thylakoid membrane structure. The antibiotic also inhibited light-dependent oxygen evolution in Synechococcus cells and in spheroplasts. These data support our conclusion that cyanobacterin specifically inhibits photosynthetic electron transport. This activity is similar to herbicides such as 3-(3,4-dichlorophenyl)-1,1-dimethyl urea (DCMU). The anhydro analog of cyanobacterin had no biological activity.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 15
    Electronic Resource
    Electronic Resource
    Springer
    Archives of microbiology 130 (1981), S. 339-343 
    ISSN: 1432-072X
    Keywords: Leptospira ; Halophilic ; Electron microscopy ; X-ray analysis ; Inclusions ; Cytoplasmic tubules
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The morphology of cells of strain Muggia, a slightly halophilic leptospire, was examined by the negative staining technique. The ultrastructure of the cells was rather similar to that of cells of Leptonema illini, i. e. the cells possessed cytoplasmic tubules. The basal complex of their flagella, however, was similar to the corresponding part of flagella on Gramnegative bacteria. The interior of the cells was densely packed with inclusions, except for the two outermost wavelengths at each end where these inclusions were absent. X-ray microanalysis showed that the inclusions contained sodium and chlorine as their main constituents. The inclusions disappeared upon storage of the cultures at room temperature.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 16
    Electronic Resource
    Electronic Resource
    Springer
    Archives of microbiology 121 (1979), S. 9-15 
    ISSN: 1432-072X
    Keywords: R-Bodies ; Kappa particles ; Free-living hydrogen bacteria ; Induction ; Electron microscopy ; Chemical composition ; Defective prophages ; Plasmids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract R-Bodies have been found in a recently isolated pseudomonas-like free-living hydrogen oxidizing bacterium. Their isolation, fine structure and chemical composition are described and compared with the R-bodies from the kappa particles (Caedobacter), obligate endosymbionts of Paramecium aurelia. The 2K 1 R-bodies exhibited essential characteristics of the kappa R-bodies; however, their size and some other structural aspects proved that they represent a new type of R-bodies. The presence of phage tail-like particles in cells induced with Mitomycin C is in favour of the hypothesis that the R-bodies might be coded by defective prophages, or by extrachromosomal elements.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 17
    ISSN: 1432-072X
    Keywords: Ribulose bisphosphate carboxylase ; Quaternary structure ; Molecular weight ; Electron microscopy ; Cyanobacteria ; Synechococcus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Ribulose bisphosphate (RuP2) carboxylase from the marme cyanobacterium, Synechococcus sp., comprised both large (57,000 dalton) and small (12,000 dalton) subunits. The undissociated, purified enzyme was considerably smaller than the spinach enzyme when compared by pore-gradient electrophoresis, gel filtration and density-gradient centrifugation. This suggested that the cyanobacterial enzyme might have a hexameric (L6S6) subunit structure, unlike the enzymes from spinach and many other organisms which are octamers (L8S8). However, the molecular weight of the Synechococcus enzyme was measured by equilibrium sedimentation and found to be 530,000, which is within the range observed for L8S8-type enzymes. Furthermore, electron microscopic studies of negatively stained preparations of both the native enzyme, and a preparation depleted of 87% of its small subunits by repeated mild-acid precipitation, revealed four-fold symmetry characteristic of an octameric, cubical structure. Synechococcus RuP2 carboxylase therefore must be an L8S8 octamer and its anomalous pore-penetration behaviour may be due to an asymmetric shape. Some support for the latter possibility was provided by electron miscoscopic observations of two different types of images which may be different views of the molecule in two planes.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 18
    Electronic Resource
    Electronic Resource
    Springer
    Archives of microbiology 140 (1984), S. 265-270 
    ISSN: 1432-072X
    Keywords: EcoRI ; EcoRI-DNA complexes ; EcoRI* activity ; Recognition sites ; Frequency of binding ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Electron microscopy of negatively stained isolated restriction enzyme EcoRI revealed particle projections with triangular or square outlines, indicating that the enzyme, in its tetrameric state, is tetrahedron-like. The two dimers making up the tetramer appear to be arranged in two planes orthogonal to each other. Complexes formed by EcoRI with the plasmids pBR322 or pGW10 were investigated by electron microscopic spreading techniques. In the presence of Mg2+, EcoRI was bound to the DNA molecules to form pearl necklace-like aggregates. The number of bound EcoRI particles was much higher as the sum of EcoRI-and 5′..AATT..3′ sites (with exceptions, the 5′..AATT..3′ sites may function as one type of EcoRI* sites) along the DNAs, indicating unspecific binding. In the absence of Mg2+, EcoRI was bound to the DNA only at the recognition site for EcoRI and the sites where the tetranucleotide sequence 5′..AATT..3′ was present. A direct correlation of the local concentrations of the bases A and T within the flanking sequences of the binding sites with the frequency of EcoRI to the DNA was observed. Dimers and tetramers of the enzyme was found to bind to the DNA. Tetramers occasionally exhibited two binding sites for DNA as indicated by the observation of DNA loops originating at the sites of bound tetrameric EcoRI particles.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 19
    Electronic Resource
    Electronic Resource
    Springer
    Archives of microbiology 123 (1979), S. 173-181 
    ISSN: 1432-072X
    Keywords: Bacillus subtilis ; Cell cycle ; DNA replication ; Cell division ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Bacillus subtilis strain Marburg was grown exponentially with a doubling time of 65 min. To follow the time course of various cell cycle events, cells were collected by agar filtration and were then classified according to length. The DNA replication cycle was determined by a quantitative analysis of radioautograms of tritiated thymidine pulse labeled cells. The DNA replication period was found to be 45 min. This period is preceded and followed by periods without DNA synthesis of about 10 min. The morphology and segregation of nucleoplasmic bodies was studied in thin sections. B. subtilis contains two sets of genomes. DNA replication and DNA segregation seem to go hand in hand and DNA segregation is completed shortly after termination of DNA replication. Cell division and cell separation were investigated in whole mount preparations (agar filtration) and in thin sections. Cell division starts about 20 min after cell birth; cell separation starts at about 45 min and before completion of the septum.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 20
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 200 (1979), S. 15-27 
    ISSN: 1432-0878
    Keywords: Lymph vessels ; Testis ; Man ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The distribution of lymph vessels in the human testis was investigated using ink injection methods, and light and electron microscopy. Lymph capillaries occur in the septula testis but are absent in the intertubular tissue. They consist of endothelial cells provided with an incomplete basal lamina and anchoring filaments of the adjacent connective tissue. Frequently, the endothelial cells are separated by gaps measuring up to 2μm. The lymph capillaries of the septula testis are connected to lymph vessels in the rete testis and tunica albuginea. These vessels have occasional smooth muscle cells and valves. At the posterior margin of the testis, the network of lymph vessels merges into collecting ducts, which together with vessels derived from the rete testis are drained by the lymphatic system in the spermatic cord.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 21
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 200 (1979), S. 329-334 
    ISSN: 1432-0878
    Keywords: Median eminence ; Axon terminals ; Tanycytes ; Electron microscopy ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The present ultrastructural study proves the existence of nerve terminals closely apposed to the plasmalemmata of tanycytes in the rat median eminence. Several of these “axo-tanycytic” endings display remarkable accumulations of agranular endoplasmic reticulum in the form of pleomorphic vesicles which are closely apposed on either side of the plasma membrane of each cell compartment. Some of these vesicular profiles give the impression of structural continuity across both membrane systems. This phenomenon is discussed in the context of being a potential substratum for communication between both cell compartments.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 22
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 200 (1979), S. 337-344 
    ISSN: 1432-0878
    Keywords: Glomerulo-tubular feedback ; Tight junctions ; Macula densa ; Distal tubule ; Electron microscopy ; Freeze fracture ; Horseradish peroxidase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In the present study the tight junctions at the macula densa were compared to those of the adjacent straight and convoluted segments of the distal tubule using freeze fracturing and thin sectioning techniques. Only insignificant differences were found in the number of strands and the apico-basal depth of the tight junctions in the three distal tubular segments of rat, dog and tree shrew. In experiments with horseradish peroxidase on mice and tree shrews, the tracer did not penetrate the apical junctions in any of the distal tubular segments. Our findings do not support the concept of considerably higher permeability of the tight junctions at the macula densa, as previously reported. Gap junctions were never observed in the distal nephron. The present results suggest that the glomerulo-tubular feedback is more likely to be mediated by transcellular resorption of solutes than by passive diffusion through a leaky paracellular shunt pathway.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 23
    ISSN: 1432-0878
    Keywords: T-lymphocytes ; Blast cells ; Lymph node ; Electron microscopy ; Stereology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Changes in the volumes and surfaces of subcellular compartments of unstimulated small lymphocytes and immunoblasts in mouse axillary lymph nodes have been established using stereological techniques. Blast transformation was induced in vivo with dinitrochlorobenzene (DNCB). Cell samples were obtained by random sampling regimes applied at light and electron microscopic levels. From electron micrographs the volume densities of euchromatin, heterochromatin, nucleoli, mitochondria, Golgi apparatus and rough endoplasmic reticulum were determined. Cell surface/volume ratios were also computed. By estimating mean nuclear volumes using light microscopy, it was possible to calculate absolute compartmental volumes and to evaluate the plasma membrane surface areas of average cells. Transformation in this model was characterized by a considerable cellular hypertrophy and a substantial increase in plasmalemma surface. Hypertrophy was the consequence of increases in the volumes of all measured intracellular compartments, notably euchromatin and “residual cytoplasm” (including ground cytoplasm and free ribosomes). These changes are discussed in the context of the altered metabolic status of cells.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 24
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 200 (1979), S. 435-442 
    ISSN: 1432-0878
    Keywords: Fat body ; Calliphora ; Electron microscopy ; Cytochemistry ; Ecdysterone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In the larval fat body of Calliphora erythrocephala, protein accumulation and autophagic activity occur prior to the onset of puparium formation. The involvement of the lysosomal system in the degradation of sequestered protein and cell organelles can be demonstrated by the electron microscopical cytochemical localization of the lysosomal marker enzyme acid phosphatase in so-called protein granules. These granules contain not only newly synthetized or absorbed protein but also remnants of cell organelles such as mitochondria and endoplasmic reticulum. Ligation of the larvae behind the brain-ring gland complex prevents the appearance of these acid phosphatase positive granules. They can be induced in ligated larvae by the injection of 20 hydroxyecdysone into the abdomen. These findings are briefly discussed in relation to the role of moulting hormones in normal development, especially with regard to the induction of autophagic activity.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 25
    ISSN: 1432-0878
    Keywords: Lipid absorption ; Pyloric caeca ; Electron microscopy ; Feeding experiment ; Rainbow trout
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Rainbow trout were killed 4 and 18 h after being fed wax ester-rich marine Zooplankton and the absorptive epithelium of the pyloric caeca examined by electron microscopy. Numerous osmiophilic drops were seen in the lamina propria underlying the epithelium of fish killed at both times, but these drops were only abundant within columnar epithelial cells of fish killed 4 h after feeding. Pinocytotic profiles were not common at the luminal plasma membranes, nor were osmiophilic droplets seen in the terminal web area between the luminal plasma membrane and the extensive smooth endoplasmic reticulum. Numerous osmiophilic droplets, 30–100 nm in diameter, were present in the cisternae of the smooth endoplasmic reticulum with up to five separate droplets per individual cisterna. Columnar epithelial cells also contained up to 100 large osmiophilic drops (“conglomerates”) which tended to be concentrated in the supranuclear (Golgi) regions. The conglomerates were 250–1200 nm in diameter and were themselves made up of smaller droplets 30–400 nm in diameter. Conglomerates were present both within intracellular membranes and free in the cytoplasm. Osmiophilic droplets in the intercellular spaces and lamina propria were similar in size to individual droplets within conglomerates. We conclude that triacylglycerols are elaborated in the smooth endoplasmic reticulum, transferred to and processed in the Golgi region and finally discharged serosally as chylomicron-like particles of not greater than 400 nm diameter.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 26
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 198 (1979), S. 477-486 
    ISSN: 1432-0878
    Keywords: Embryonic heart ; Myogenesis ; Sarcomere ; Crustacea (Homarus americanus) ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Cardiomyoblasts in the myocardium of embryonic lobsters at 3–4 weeks and 6 months of development were examined with the transmission electron microscope in order to describe the events in the formation of sarcomeres in a neurogenic cardiac system. Thick and thin myofilaments appear first in the cell periphery near the sarcolemma. They align in parallel in a sequential fashion to form consecutive sarcomeric units. Well-defined A and I bands appear before any semblance of a Z line is present. The initial sarcomere is anchored to the sarcolemma by the insertion of thin myofilaments into a region of electron dense material associated intimately with the sarcolemma. Myofibrils grow outward in several planes away from the electron-dense regions of membrane that serve as focal points for myofibril formation.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 27
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 198 (1979), S. 521-526 
    ISSN: 1432-0878
    Keywords: Adenohypophysis ; Electron microscopy ; L-DOPA ; Lysosomes ; Chinese quail, Excalfactoria chinensis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Intraperitoneally injected L-DOPA was found to stimulate strongly the lysosomal system of all of the cell types of the adenohypophysis. We suggest that this amine may play a role in the regulation of the secretory activity of the gland by mediating the lysosomal activity, this role being of variable importance according to the fluctuations in hormonal activity. Ultrastructural changes occur in some cell types following injection of L-DOPA. The question as to whether these changes are induced directly by L-DOPA or via the monoaminergic system of the hypothalamus and its hypophysiotropic hormones is discussed.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 28
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 199 (1979), S. 509-517 
    ISSN: 1432-0878
    Keywords: Olfactory bulb ; Giant cells ; Neurosecretion ; Electron microscopy ; Labyrinth fish
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The giant cells in the olfactory bulb of labyrinth fish, most likely belonging to the nervus terminalis, show ultrastructural features of active synthesis of secretory material. Dense core vesicles (70–100 nm in diameter), found in the perikaryon as well as in the axon, are the possible storage sites of the secretory substance. Its chemical nature is unknown. In some of these vesicles acid phosphatase is demonstrable. Large membrane-bound bodies (up to 2000 nm in diameter), either containing an electron dense matrix or debris of cytoplasmic organelles, are also acid phosphatase-positive, suggesting their lysosomal nature. Some other ultrastructural characteristics of these cells are also described.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 29
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 237 (1984), S. 219-226 
    ISSN: 1432-0878
    Keywords: Spermatogonia ; Spermatocytes ; Carbohydrates ; Guppy ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The structure of guppy (Poecilia reticulata) spermatogonia and spermatocytes has been studied using electron microscopy. The spermatogonia, situated at the apex of the seminiferous tubule, are almost all surrounded by a network of Sertoli cells; they have very diffuse chromatin and one or two large nucleoli. The cytoplasm contains relatively few organelles, although annulate lamellae are found. The mitochondria have few cristae and are concentrated at one pole of the cell; they are sometimes found with intermitochondrial cement. These spermatogonia are separated from each other, having no intercellular bridges or inclusion in Sertoli cells, and are relatively undifferentiated; they correspond to stem cells. The spermatogonia beneath the apex are organized into cysts. First-generation spermatogonia are more dense and heterogeneous, their nuclei becoming smaller and their chromatin becoming denser during successive generations. In spermatocytes, the synaptinemal complex exists as a modified form until metaphase. The concentration of organelles in the cytoplasm increases and the organelles become more diversified as spermatogenesis progresses. Many cytoplasmic bridges are observed (several per cell), indicating that the cells remain in contact after several divisions. These changes in germ cell structure have been related to some of the characteristic features of spermatogenesis in guppy, e.g. the large number of spermatogonial generations and the complexity of spermiogenesis.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 30
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 201 (1979), S. 159-163 
    ISSN: 1432-0878
    Keywords: Insulin secretion ; Acid-base changes ; Electron microscopy ; Pancreas perfusion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ultrastructural changes in pancreatic β cells were studied following glucose-induced insulin secretion in vitro, at two different extracellular pH (7.4 and 7.8). The pancreata perfused at pH 7.4 exhibited a biphasic insulin response to glucose challenge together with signs of increased emiocytotic activity and numerous microtubules in the β cells. Conversely, the pancreata perfused at pH 7.8 showed a significant decrease in insulin secretion, and their β cells revealed scarce emiocytotic images and a marked increase of intracellular granulolysis. These results represent the ultrastructural correlate of the reduced insulin secretion produced by metabolic alkalosis in the perfused rat pancreas.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 31
    ISSN: 1432-0878
    Keywords: Adrenal cortex ; Steroid release ; Rabbit ; Electron microscopy ; Morphometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The fine structure of the rabbit adrenal cortex was investigated. The parenchymal cells display the ultrastructural features of steroid-producing cells, and also contain numerous electron-dense bodies frequently located near intercellular canaliculi, which open into the subendothelial space. Short-term ACTH-administration induced a noticeable decrease in the volume of the lipid compartment in the cells of all three cortical zones and a significant increase in the volume of dense bodies in the cells of zona fasciculata and zona reticularis. The hypothesis that these dense bodies are secretory granules is discussed in the light of biochemical evidence showing that ACTH increases the concentration of both corticosterone and cortisol in the decapsulated-enucleated adrenal homogenate and does not affect the activity of two lysosome-marker enzymes (i.e., acid phosphatase and β-glucuronidase).
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 32
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 238 (1984), S. 413-416 
    ISSN: 1432-0878
    Keywords: Peroxisomes ; DAB-cytochemistry ; Electron microscopy ; Liver, amphibian ; Gymnophiona ; Ichthyophis glutinosus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ultrastructure of hepatic peroxisomes was investigated in Ichthyophis glutinosus (Amphibia: Gymnophiona), employing perfusion fixation and the diaminobenzidine (DAB) technique for the visualization of catalase. The majority of peroxisomes is circular or rod-shaped, although elongated particles occasionally occur. They contain a finely granular matrix, lightly stained after the DAB procedure. Their mean diameter is approximately 0.25 μm. Serial sections reveal that the circular and rod-shaped peroxisomal profiles are cross and oblique sections of highly tortuous, tubular organelles exceeding 2 μm in length. In addition to tubular profiles, elongated, rectangular particles, as well as straight dumbbell-shaped organelles with distinct marginal plates are observed. They range from 900 to 1650 nm in length (mean = 1200 nm). In the flattened, thin central portion of the dumbbell-shaped particle, the peroxisomal membranes form a cisterna enclosing one or two uniformly thick marginal plates, which display a definite substructure with a periodicity of 10 nm. These findings indicate that peroxisomes in the liver of Ichthyophis exhibit a complex organization. It is suggested that the organelles undergo a specific differentiation process, morphologically characterized by the formation of enlarged segments of unusual shape.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 33
    ISSN: 1432-0878
    Keywords: Ovulation (rabbit) ; Graafian follicle ; Perfusion ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Isolated ovaries from untreated, sexually mature rabbits were introduced into an in vitro perfusion system and perfused with a chemically defined medium containing albumin. The ovaries were perfused for up to 15 h (mean 11.5 h) and then processed for morphological investigation. Both at the light- and electron-microscopical levels, most of the ovaries exhibited a normal structure comparable with ovaries in situ. In two cases, however, marked accumulations of bacteria were found, although not inside the follicles. Since ovulation in the rabbit normally occurs between 9.5–13 h after mating or human chorionic gonadotrophin treatment, this model seems adequate for studies of ovulation in vitro. It is, however, important to study the ovaries microscopically after the perfusion to detect artifacts, e.g., bacterial infection, that may have influence on the process of ovulation.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 34
    ISSN: 1432-0878
    Keywords: Tannic acid ; Acetylcholine receptors ; Tissue culture ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Spinal cord neurons from 9-day chick embryos were maintained in culture for up to 35 days and then fixed in 4% cacodylate-buffered glutaraldehyde containing 2% tannic acid. After about 15 days in culture a small percentage of the synaptic specializations present were characterized by striking electron-dense striations averaging 15 nm in width, oriented perpendicular to the postsynaptic membrane. These structures increased in frequency with time in culture (to a maximum of about 10% of all synapses in the oldest cultures); they were asymmetrical, protruding approximately 8 nm into the synaptic cleft, and more deeply (approximately 15–18 nm), into the postsynaptic cytoplasm. On the basis of earlier work by Sealock (1980) they are interpreted as concentrations of acetylcholine receptors. Similar membrane differentiations were also seen associated with active-zone areas of a few presynaptic membranes, and the possibility that these represent presynaptic acetylcholine receptors is discussed. Additional observations reported are (1) the presence of striations resembling those seen at the postsynaptic membrane in the membranes of some postsynaptic vesicles, and (2) filamentous links between the striations and cytoskeletal elements of the postsynaptic cell.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 35
    ISSN: 1432-0878
    Keywords: Monoamine-containing cells ; Taste bud ; Paracrine cells ; Mechanoreceptors ; Electron microscopy ; Teleosts
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The taste buds on the barbels in three species of teleosts (Cyprinus carpio, Misgurnus anguillicaudatus, Parasilurus asotus) were studied by means of fluorescence and electron microscopy. Intensely yellow-fluorescent cells, which are disk-shaped and located exclusively in a basal position, are observed in the barbel-buds of all fishes examined. The basal cells contain a large number of small clear vesicles approximately 40–60 nm in diameter, which show a tendency to aggregate in the cytoplasm facing the junction of the nerve terminals; chemically transmitting synapses are seen in the latter region. It is suggested from the present observations that the basal cells in the barbel-bud may originate from Schwann cells and have a dual function both as mechanoreceptors and paracrine elements. Since the administration of 5,6-DHT results in an appearance of small dense vesicles among the small clear vesicles, the possibility exists that the basal cell may be capable of taking up monoamines and storing them in the small clear vesicles.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 36
    ISSN: 1432-0878
    Keywords: Exocrine pancreas ; Calcium pool ; Calcium release ; Electron microscopy ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In an attempt to identify a cellular Ca2+-pool, from which calcium is released when secretagogues are applied, tissue fragments of the rat exocrine pancreas were incubated and fixed with glutaraldehyde in the presence of calcium. By means of this procedure electron-dense deposits were found on plasma membranes. X-ray microanalysis showed that these deposits contain calcium. Stimulation of tissue fragments with the use of the secretagogues carbachol or cholecystokinin reduced the number of deposits by about 80%. When the antagonist atropine was applied after carbachol stimulation, deposits reappeared on cell membranes, which then disappeared again after a second stimulation with cholecystokinin. In the presence of procaine, carbachol was inhibited and only slightly reduced the Ca2+-deposits on the plasma membranes. These results suggest that a calcium pool, from which calcium is released to induce enzyme secretion on stimulation, is located in the cell membrane
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 37
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 199 (1979), S. 171-175 
    ISSN: 1432-0878
    Keywords: Crustaceans ; Neuromuscular synapse ; Multiterminal innervation ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The distribution of nerve terminals from a single excitatory motor axon has been followed along a fiber from the proximal accessory flexor muscle of the lobster by thin serial sectioning at periodic intervals. The excitatory motor axon provides small axonal branches (diameter 5–12 μm) of varying lengths that travel along the surface of the muscle fiber. Each of these branches gives rise to discrete synaptic terminals which are not uniformly distributed. Individual terminals vary in length from 10–60 μm and the majority possess neuromuscular synapses. The greatest distance between synapses is slightly over 1 mm which is well within the length constant (2.6 mm) of this muscle fiber. Thus the spatial distribution of synapses is such as to ensure adequate depolarization along the entire length of the muscle fiber.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 38
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 199 (1979), S. 281-288 
    ISSN: 1432-0878
    Keywords: Annular microtubules ; Nodes of Ranvier ; Nerve ; Axon ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Using a special albumin technique, nodes of Ranvier have been examined within frog skeletal muscle, sciatic nerve and rat and frog cerebrum. Initial segments have been examined in cerebrum of frog and rat. Microtubules usually run longitudinally through these regions, but within the bare area of the intramuscular node of Ranvier, annular or helical bundles of microtubules run in a marginal band at right angles to the more centrally placed longitudinal microtubules. These nodal bare areas show a pronounced convexity and it is suggested that the annular microtubules serve to maintain this convexity during muscle contraction.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 39
    ISSN: 1432-0878
    Keywords: Chloride cells ; Acid stress ; Gill ; Electron microscopy ; Fathead minnow
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Fathead minnows, Pimephales promelas, were exposed for 129 days to Lake Superior water acidified with sulfuric acid by means of a flow-through toxicant injection system. The effects of chronic acid stress (pH 6.5, 6.0, 5.5, 5.0) on gill histology were examined. Most of the histological effects were seen at pH 5.5 and 5.0 and were confined primarily to changes in numbers, distribution, and morphology of chloride cells. At low pH levels there tend to be more chloride cells in the gill epithelium and an increased percentage of these cells in the secondary lamellae. In contrast to normal chloride cells, chloride cells from fish exposed to low pH frequently had apical pits while some had bulbous apical evaginations. The occurrence of structural changes in chloride cells during exposure to acid water suggests that chloride cells may be involved in acclimation to acid stress.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 40
    ISSN: 1432-0878
    Keywords: Lactating cell ; Lipid droplets ; Secretory vesicles ; Mitochondria ; Intracellular associations ; Electron microscopy ; Milk secretion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The size, cellular location, and identity of surface-associated components were determined for lipid droplets in lactating cells. Transmission electron-microscopic measurements were made involving 3801 droplets in approximately 211 cells from three rats and 1197 droplets in 66 cells from a mouse. For the purposes of droplet evaluation, cells were divided into seven locations ranging from basal to secreting positions. Droplets were also categorized with respect to contact with other droplets, basolateral plasma membrane, mitochondria, Golgi apparatus, secretory vesicles, and endoplasmic reticulum-cytoplasm (ERC). Data on droplet size showed that droplet growth occurs mainly in the secretory position, confirming previously published findings. Lipid droplets from mouse tissue, although somewhat smaller in size showed similar growth trends to those of the rat. Data on numbers of droplet contacts and percentages of droplet circumferences involved in associations with other cell components showed that the dominant interaction of lipid droplets was with the ERC. However, intimate association of droplets with mitochondria was noted in all cellular locations. In addition, nursed animals exhibited a greater proportion of droplet surface association with secretory vesicles and less in contact with mitochondria in comparison to those not nursed. The significance of these relationships to milk synthesis and secretion is discussed.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 41
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 236 (1984), S. 249-255 
    ISSN: 1432-0878
    Keywords: Oocyte ; Nucleolus ; Silver staining ; Electron microscopy ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The nucleoli of dictyate-stage growing oocytes in rat ovaries were examined both with routine electron microscopy and electron microscopy after silver nitrate and ammoniacal silver nitrate (Ag-AS) staining. The nucleoli of the unilaminar follicular oocytes consist of twisted strands of dense fibrillar components, aggregates of granular components, and small fibrillar centers. After Ag-AS staining, silver grains are numerous on the dense fibrillar strands, fewer on the fibrillar centers, and very sporadic on the granular aggregates. The same stainability of three nucleolar components with the Ag-AS method was also confirmed in the nucleoli segregated by actinomycin D. During the transition of growing oocytes from bilaminar to plurilaminar follicle stage, the nucleolar dense fibrillar strands gradually conglomerate and are transformed into large and compact spherules. The stainability of dense fibrillar components with the Ag-AS method was lost along with this nucleolar transformation. These results may provide some new clues on the functional significance of AgAS-positive proteins in the nucleoli.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 42
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 201 (1979), S. 37-44 
    ISSN: 1432-0878
    Keywords: Brush cell ; Receptor ; Lateral microvilli ; Gallbladder ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The brush cells of the gallbladder epithelium of the mouse have microvilli not only at their luminal border but also on their lateral surface, from the level of the nucleus to the junctional complex. The lateral microvilli radiate from the brush cell in all directions, contain a core of filaments, and penetrate up to 3 μm into the adjacent cells. The microvilli in these locations display small desmosomes at their base.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 43
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 201 (1979), S. 451-458 
    ISSN: 1432-0878
    Keywords: Epididymis ; Freeze-fracture ; Electron microscopy ; Male reproduction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The epithelium of the monkey epididymis was studied by means of freeze-fracture techniques and conventional electron microscopy. For the study of transepithelial permeability lanthanum hydroxide was used as an intercellular tracer. The epididymal epithelium consists mainly of tall columnar cells. The long stereocilia at the apical surface, similarly to microvilli, exhibit after freeze-fracture, two distinct faces: the E face, concave and with fewer membrane-associated particles, and the complementary convex P face. In the lumen unusual groups of smooth-surfaced vacuoles are present. A tight junctional network, which shows some permeability to the lanthanum tracer, is located at the apical end of the cells. Supranuclear cross-fractures clearly show the well developed Golgi cisternae and numerous vacuole profiles. The highly infolded, centrally located nucleus exhibits, after freeze-fracture, an even distribution of nuclear pores. In the perinuclear region the rough endoplasmic reticulum, which also presents pores, displays a sheet-like organization. The basal cytoplasm is filled by numerous globular profiles of membrane-bounded granules. Freeze-cleave exposes large cytoplasmic areas where the types and amount of organelles indicate an intense metabolic activity.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 44
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 201 (1979), S. 467-477 
    ISSN: 1432-0878
    Keywords: Anterior pituitary ; Hormone synthesis ; Morphometry ; Autoradiography ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In order to compare the functional state of the anterior pituitary of spontaneously hypertensive rats (SHR) with that of normotensive Wistar Kyoto rats (WKR), the anterior pituitary was examined by morphometry and autoradiography at the level of electron microscopy. The relative number and the relative volume of thyrotrophs in the anterior pituitary were significantly greater in SHR compared with age-matched WKR at 0, 7, 30–33 days, and 10 months of age, while the relative number of somatotrophs in SHR was significantly smaller at 1 and 10 months of age. Electron microscope autoradiographic analysis of uptake of 3H-lysine by thyrotrophs of both strains at the age of approximately one month showed that 3H-lysine was incorporated into protein and transported finally to secretory granules which migrated to near the cell membrane to be discharged. Silver grains were significantly more numerous over the thyrotrophs of SHR than over those of WKR at 30 min, 1 h, and 4h after the injection of 3H-lysine. The present study has ascertained morphologically that a congenital hypersynthesis of TSH by the anterior pituitary occurs in SHR.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 45
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 202 (1979), S. 125-132 
    ISSN: 1432-0878
    Keywords: Macrophage ; Osteoclast ; Bone resorption ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Ultrastructural observations on macrophage-mediated resorption of calcified tissue of killed fetal long bones are described and correlated with increased 45Ca release into the medium. Macrophages disrupt calcified tissue extracellularly and appear to engulf large fragments of mineralized matrix. Ruffled borders, which are common features of osteoclasts at sites of resorption of bone, do not develop in macrophages. However, clear zones are seen in macrophages as well as osteoclasts. These findings provide additional evidence for non-osteoclast-mediated resorption of calcified tissue.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 46
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 235 (1984), S. 51-58 
    ISSN: 1432-0878
    Keywords: Parathyroid glands ; Electron microscopy ; Light microscopy ; Quantitative histology ; Mongolian gerbil
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Stereology and semi-automatic image analysis were used with the aim of comparing the structure of parathyroid glands from untreated adult Mongolian gerbils fixed by immersion with those fixed by perfusion. Subclassification of the chief cells based upon the staining affinity or electron density of the cytoplasm was readily performed only in glands fixed by immersion, and so-called atrophic cells were observed only in these glands. The atrophic cells were often surrounded by “light” chief cells. In glands fixed by perfusion, “light” chief cells were only rarely encountered. A significant difference between glands fixed by immersion and those fixed by perfusion was found only with regard to the form of cells and nuclei, those fixed by perfusion being more spherical. When comparing individual cells within glands fixed by immersion, “light” chief cells were more spherical and had a significantly larger nuclear and cellular size, and a lower mitochondrial volume density than the “intermediate”/“dark” chief cells. Otherwise there were no significant differences in any of the parameters investigated. These data indicate that occurrence of socalled “light” chief cells and atrophic cells is a result of improper fixation. The results of this study do not favour the concept of a functional cycle with a simultaneous occurrence of active and inactive cells within parathyroid glands.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 47
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 235 (1984), S. 153-158 
    ISSN: 1432-0878
    Keywords: Bovine ; Interdigitating cell ; Lymphoid tissues ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Electron-microscopic studies of lymphoid tissues from bovine fetuses and from calves disclosed a non-lymphoid cell type in the thymus-dependent zones of secondary lymphoid tissues and in the thymus that is distinguishable from reticulum cells, epithelial and endothelial cells, and macrophages. Based on morphological and topographical criteria, the cell is identified as the interdigitating cell. In addition, studies of the tissues of normal and virus-challenged fetuses, and of conventionally reared calves, indicated that the interdigitating cells originate from monocytoid cells, which undergo differentiation in the thymus-dependent zones during an immune response.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 48
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 235 (1984), S. 243-249 
    ISSN: 1432-0878
    Keywords: Gap junction ; Electron microscopy ; Freeze fracture ; Cell-to-cell communication
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Gap junctions exist in the septa between the segments of the lateral giant axons in the ventral nerve cord of the crayfish Procambarus. A large increase in the resistance (uncoupling) of these gap junctions was brought about by mechanical injury to the axonal segments. Both thin sections and freeze-fracture preparations were used to monitor the morphological changes which occurred up to 45 min after injury. There was no apparent change in the organization (a loose polygonal array) of the intramembrane particles which make up the junctional complex up to 45 min after injury. In some instances, however, the intramembrane particles appeared to have moved away from the junctional area. Other junctional regions were internalized and appeared similar to what have been called annular gap junctions. Also at this time (20–25 min after injury), a dense cytoplasmic plug formed in uninjured axon near the junctional region. It is concluded that the gap junctions that exhibit a loose polygonal organization of the intramembrane particles may be either in a state of low resistance (coupled) or a state of high resistance (uncoupled).
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 49
    ISSN: 1432-0878
    Keywords: Ovulation ; Perfusion ; Graafian follicle (rabbit) ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Ovulation was induced in rabbits by intravenous administration of human chorionic gonadotrophin (HCG), and 4–5 h later the ovaries were isolated and introduced into an in-vitro perfusion system containing synthetic medium with albumin. Rupture of follicles occurred in vitro within the physiological time range (mean 11.3 h after injection of HCG), although with a reduced frequency. Preovulatory and ruptured follicles were studied in detail by light and electron microscopy. In the granulosa layer of ruptured or preovulatory follicles cytoplasmic blebbing activity, disappearance of CallExner bodies and differentiation toward luteinized cells were found. Perhaps the most important sign of normal preovulatory development in vitro was that the basement membrane surrounding the granulosa layer was penetrated by projections of granulosa cells. In the absence of this penetration phenomenon the granulosa layer prolapsed out of the follicle. Immediately before rupture, follicles showed marked degeneration, restricted to the outer layers of the apical wall, which is compatible with the hypothesis that degradative enzymes are released close to the surface of preovulatory follicles. Although the majority of follicles that ovulated under in-vitro conditions showed the same kind of morphological alterations as can be seen in vivo, occasional atypical ruptures occurred without any overt signs during perfusion. Also technical manipulations of the perfusion system, e.g., nonphysiological increase of perfusion pressure, could force follicles to rupture. This illustrates the importance of careful morphological study of all ovaries perfused in vitro before conclusions are drawn.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 50
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 237 (1984), S. 149-154 
    ISSN: 1432-0878
    Keywords: Pituitary gland, pars distalis ; Innervation ; Synaptoid contacts ; Electron microscopy ; Rana temporaria L
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In the pars distalis of the hypophysis of adult Rana temporaria, three types of nerve-fiber profiles were found at two distinct sites, in both lateral parts of the bordering regions of the anterior lobe with the intermediate lobe of the hypophysis. The first type of nerve-fiber profile consists of bundles of very fine axonal elements (diameter: 〈0.7 μm). The second type is formed by larger nerve fibers (diameter up to 4 μm) containing a few neurosecretory granules of approximately 100 nm. The third type of nervefiber profile resembles the second type but these nerve fibers make synaptoid contacts on at least two different types of glandular cells. The possible functional significance of these nerve fibers in the pars distalis is discussed. No nerve fibers were found (1) in the central part of the bordering region of the pars distalis with the intermediate lobe, (2) at the bordering region with the median eminence and (3) with the neurohypophysial stalk, and (4) in all other parts of the pars distalis.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 51
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 201 (1979), S. 101-127 
    ISSN: 1432-0878
    Keywords: T-lymphocytes ; Cell activation ; Stereology ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Stereological data of phytohaemagglutinin (PHA)-activated human T-lymphocytes were recorded at intervals (12 to 72 h) together with biochemical (isotope-uptake, lymphotoxin-release) and morphological measurements. About 98 % of the cells were activated 12 h after PHA-stimulation. The activation phase lasted less than 48 h, i.e., cells entering the activation phase within 12 h were at their activation maximum by 48 h. The activated cell increased in size. The nuclear/cytoplasmic-ratio decreased. Most of the cytoplasmic organelles developed in phase with the increase of cytoplasmic volume. After 48 h, mitotic figures were frequently seen. Due to the increasing number of secondary, activated daughter cells, parameters of most cytoplasmic components declined between 48 and 72 h. Structural changes in the nucleus preceded the 3H-leucine uptake, which had not reached its maximum after 72 h of incubation. The 3H-leucine uptake started as early as 12 h after culture initiation, and its increase was proportional to the increasing polyribosome density. No maximum uptake was reached up to 72 h, but the development of structural components related to this uptake was at its maximum at the end of the activation phase (48 h). The formation of bound ribosomes occurred subsequent to the enlargement of the surface of the rough endoplasmic reticulum. Initial polysome formation occurred at the expense of existing free ribosomes.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 52
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 201 (1979), S. 459-466 
    ISSN: 1432-0878
    Keywords: Electron microscopy ; Collagen ; Cuticle ; Lumbricus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary A method has been developed to isolate and purify cuticular fibrils of Lumbricus. Polarizing microscopy confirms the collagenous nature of the isolated fibrils. Study in the electron microscope of isolated fibrils, negatively or positively stained, shows that they are cylindrical, unbranching and without periodic structure. Enzymatic treatment of cuticles with alpha-amylase and trypsin results in a more or less complete dissociation of the fibrils which appear clearly to be made up of helically wound bundles of filaments (30–40 Å). The structure of the cuticular fibrils is discussed in relation to biochemical and biophysical data and compared to the ultrastructural organization of other periodically cross-banded fibrils.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 53
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 238 (1984), S. 165-175 
    ISSN: 1432-0878
    Keywords: Mesonephros ; Pig embryo ; Glomerulus ; Microvasculature ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Vascularization of the pig mesonephros was investigated in embryos 5–8 cm in length. Vascular injections with microfil were cleared and dissected; corrosion casts were studied under the scanning electron microscope (SEM). Perfusion-fixed tissue was used for SEM and transmission electron microscope (TEM) studies, including freeze-fracture specimens. The branches of one mesonephric artery carry up to 15 glomeruli. Several glomeruli occupy the same arterial branch, with very short afferent arterioles proper. The efferent vessels, frequently 2–5, leave the extensive vascular pole opposite the entering arteriole and split into peritubular capillaries radiating towards the superficial veins. These capillaries form vascular regions in the shape of flattened pyramids. Along its course, one nephron is supplied by vessels derived from 4–7 glomeruli. The nephrons have less vascular contact than in the definitive kidney. The ultrastructure of the single mesonephric vessels matches the metanephric counterparts. Epithelioid cells with renin granules are common in afferent arterioles, larger arteries, and efferent vessels. The lobulated glomeruli are up to 750 μm long and flattened, showing the usual features of podocytes, mesangial cells, and an attenuated endothelium with fenestrations between 50 and 250 μm. It partially retains its own basement membrane. There is no proximal mesangium.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 54
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 238 (1984), S. 387-394 
    ISSN: 1432-0878
    Keywords: Pacinian corpuscles, cat ; Denervation ; Atrophy ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ultrastructure of Pacinian corpuscles of the cat located in the crural region and innervated by the interosseous nerve was studied 1 to 14 months after denervation. Both the Pacinian inner core and capsule remained well preserved one month after denervation. However, the denervated inner cores underwent progressive atrophy and wasting, which resulted in a gradual reduction of the amount of inner-core cells and lamellae, widening of interlamellar clefts, formation of empty spaces in the axial region and a considerable increase in the number of collagen fibrils. In spite of the wasting, the inner core still survived 14 months after denervation, but at least half of its volume became occupied by collagen fibrils which surrounded the remaining inner-core cells and lamellae. Collagen fibrils assembled in the denervated core were markedly thinner than those found in the capsule, as is also the case in normal Pacinian corpuscles. In the capsule, discrete focal degeneration, occasional pyknosis of the innermost capsular cells and macrophage infiltration were observed from the first month after nerve section onward, but the number of capsular layers remained within the normal range (30–40) up to 14 months after denervation.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 55
    ISSN: 1432-0878
    Keywords: Lymph (pig) ; Langerhans cells ; Phase contrast microscopy ; Histochemistry ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Large mononuclear cells with long, actively moving cytoplasmic veils were observed in lymph coming from the skin. The enzyme histochemistry and ultrastructure of these cells suggested that they are related to epidermal Langerhans cells and interdigitating cells in the lymph node. It has been reported that Langerhans cells and interdigitating cells play a role in contact hypersensitivity by taking up antigen and presenting it to thymus-dependent lymphocytes, and it is likely that the veiled cells in the lymph are also involved. After skin-painting with 1-fluoro-2,4-dinitrobenzene (DNFB), the veiled cells in lymph coming from the site of painting became more active and were observed contacting other cells present in the lymph; many large cellular aggregates were found. Since neutrophilic leucocytes and mononuclear phagocytes were the predominating cell types in this lymph, there was no evidence for a massive recruitment of immunocompetent lymphocytes at the site of painting. Neonatally thymectomized pigs do not develop allergic reactivity to DNFB. It is of interest that the number of veiled cells and their ability to form large cellular aggregates was not affected in these animals. Therefore, it is unlikely that the defect in responsiveness can be attributed to a failure in the function of veiled cells.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 56
    ISSN: 1432-0878
    Keywords: Pancreatic islets ; Adrenergic innervation ; Insulin secretion ; Chemical sympathectomy ; Adrenalectomy ; Fluorescence histochemistry ; Immunohistochemistry ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Morphological changes in the adrenergic innervation of pancreatic islets after chemical sympathectomy by use of 6-hydroxydopamine and the influence of the sympatho-adrenal system on insulin secretion were investigated in the mouse and rat. Fluorescence histochemistry revealed a clear-cut reduction in the number of adrenergic nerve fibers in the pancreatic islets 2 days after administration of 6-hydroxydopamine; the reduction was more pronounced in the rat than in the mouse. In the rat, a partial regeneration was seen after 6 weeks. In the pancreas of the mouse, after administration of 6-hydroxydopamine, a severe damage of unmyelinated nerve fibers was revealed electron microscopically. However, no ultrastructural or immunohistochemical alterations could be demonstrated in the endocrine cells of the islets. 6-Hydroxydopamine induced a depression of basal plasma insulin concentrations in mice and an elevation in rats. Adrenalectomy depressed basal plasma insulin levels in mice. The α-adrenoceptor antagonist phentolamine enhanced insulin secretion in normal mice. The secretory response of insulin to phentolamine was diminished by chemical sympathectomy and almost abolished by adrenalectomy or the combination of chemical sympathectomy and adrenalectomy. Thus, the effect of phentolamine is probably mediated by liberated catecholamines. It is concluded that basal insulin secretion is partially regulated by the sympatho-adrenal system and that species differences exist in this respect. In addition, the results suggest that endogenous catecholamines have the ability to promote insulin secretion.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 57
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 216 (1981), S. 471-479 
    ISSN: 1432-0878
    Keywords: Ovulation ; Perfusion ; Graafian follicle (Rabbit) ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In the present investigation the ultrastructure of isolated rabbit ovaries, perfused with different media for various time periods, was studied. The steroid hormone production by the perfused ovary was also determined. Perfusion with Medium 199 results in prominent interstitial ovarian oedema which increases with perfusion time. Even after the addition of 6–10 % Dextran T40, oedema appears in the interstitial tissue of the ovary. Perfusion solutions with osmotically active colloid particles of large molecular size (Dextran T70; average molecular weight 70,000 and bovine serum albumin), cause less distortion in the ovarian structure, and ultrastructurally the ovarian tissues appear essentially the same as in the control ovaries. The results indicate that the perfused rabbit ovary, under strictly controlled conditions, can be used as an experimental model for studies of various aspects of ovarian function, including follicular rupture.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 58
    ISSN: 1432-0878
    Keywords: Mitochondria ; Electron microscopy ; Stereology ; Number and volume ; Lymphocytes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The authors ask the question whether the parameters “number” and “volume” are suitable for the morphometric analysis of mitochondria. In several types of cell, irregularity of mitochondrial shape makes it technically difficult, if not impossible, to obtain reliable stereological estimates of mean organelle volume or number per unit volume. Of more fundamental concern is whether number of mitochondria per cell is of any real value as a structural correlate of respiratory potential and hence as a measure of cell function. Alternative parameters might serve better for this purpose. Though the problem is illustrated by reference to quantitative studies of lymphocytes, it is also pertinent to the investigation of many other cell types.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 59
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 216 (1981), S. 205-214 
    ISSN: 1432-0878
    Keywords: Compound eyes ; Insects ; Crustaceans ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The basement membrane of the compound eye of four insect species and three crustacean species was investigated employing electron microscopy. The basement membrane consists of an extracellular (basal lamina) and a cellular portion, the latter being composed of the flattened terminal extensions of cone cells and accessory pigment cells in insects and distal pigment cells in crustaceans. Other cells can also contribute to the basement membrane. It is thus a complex structure in all well-developed compound eyes. The cellular contributions vary in different species and were found to correlate to specific taxonomic units.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 60
    ISSN: 1432-0878
    Keywords: Gastrin ; CCK ; Median eminence ; Electron microscopy ; Xenopus laevis (Amphibia, Anura)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary By use of an anti-gastrin serum and colloidal gold- or ferritin-labelled sheep anti-rabbit γ-globulins, nerve fibres and nerve terminals containing a gastrin-like substance were characterized at the ultrastructural level in the median eminence of Xenopus laevis. These immunoreactive fibres contain neurosecretory granules displaying medium to high electron density and a mean diameter of 75 nm. Labelling intensity varies from granule to granule. This is the first demonstration at the ultrastructural level of the precise location of a gastrin-like hormone in the median eminence of a vertebrate.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 61
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 217 (1981), S. 211-223 
    ISSN: 1432-0878
    Keywords: Pituitary gland ; Pars intermedia ; Electron microscopy ; Sheep
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Light microscopy of coronal sections of the sheep pars intermedia revealed a compact, incompletely lobulated V-shaped region about 15–20 cells thick, situated between the pars distalis and the pars nervosa. A prominent hypophysial cleft and follicles containing a colloid-like substance were seen. Using electron microscopy, five cell types could be distinguished: pars intermedia glandular cells, pars distalis-like glandular cells, interstitial cells, follicular cells and cleft lining cells. The polyhedral to pear-shaped pars intermedia glandular cells predominated. They contained dense-cored, membrane-bound granules near the Golgi complex, and larger, irregular vesicles with finely granular contents of varying electron density throughout the remaining cytoplasm; exocytotic release of granules was occasionally observed. Smaller numbers of cells resembling those seen in the pars distalis were scattered throughout the pars intermedia. Interstitial cells usually possessed elongated cytoplasmic processes which extended between the glandular cells, and were characterized by deeply indented nuclei, elaborate junctional complexes and an absence of cytoplasmic granules. Cells lining the follicles resembled the interstitial cells. The major cells bordering the hypophysial cleft were triangular in section and bore irregular microvilli on their free surface. The pars intermedia appeared to be less vascular than the remainder of the hypophysis and only occasional fenestrated capillaries were seen. Nerve profiles were rare.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 62
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 202 (1979), S. 63-73 
    ISSN: 1432-0878
    Keywords: Silkworm testis ; Cyst cell ; Junctions ; Freeze-fracture ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The cell junctions of the cyst envelope in the testes of Bombyx mori were examined by electron microscopy utilizing a thin-sectioning technique following conventional fixation, tannic acid fixation and lanthanum tracer study, and also using a freeze-fracture technique. There are three kinds of junctions; septate junctions, gap junctions and tight junctions. Septate junctions are of the pleated type. Gap junctions are characterized by four electron-dense lines and three electronlucent lines in the reduced intercellular spaces seen by thin-sectioning. They are of the “E” type, having clusters of intramembraneous particles on the E-fracture face. The most striking finding is the frequent presence of tight junctions on the fracture planes, while focally fused outer leaflets of the junctional unit membranes are rarely detected on thin-sectioned preparations. Tight junctions are characterized by branching zigzag ridges on the P-fracture face and complementary grooves on the E-fracture face. It is proposed that tight junctions are new morphological evidence of blood-germ cell barrier in an insect.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 63
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 203 (1979), S. 181-188 
    ISSN: 1432-0878
    Keywords: Ventral prostate ; Epithelial cells ; Electron microscopy ; Light microscopy ; Older rats
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ventral prostatic secretory epithelial cells in older rats were studied by light and electron microscopy. The cells vary in height in different parts of the same organ, and ultrastructurally they show the presence of a developed secretory apparatus such as well-developed Golgi body and abundant rough endoplasmic reticulum. They also show signs of a depressed secretory activity, involving occasional emiocytosis of apical secretory vacuoles and a paucity of condensing vacuoles in the Golgi region and above it. Further, they are characterized by the frequent occurrence of supra and paranuclear pleomorphic lysosomes.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 64
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 215 (1981), S. 643-649 
    ISSN: 1432-0878
    Keywords: T-lymphocytes ; Blast cells ; Autoradiography ; Electron microscopy ; Stereology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary As a companion to an earlier study, the morphometric attributes of stimulated (blast-derived) lymphocytes in mouse axillary lymph nodes have been established using stereological and autoradiographic methods. Blast transformation was induced in vivo with dinitrochlorobenzene (DNCB) and stimulated cells were labelled with tritiated thymidine. Random samples of cells were taken for light and electron microscopic morphometry. In comparison to the unstimulated lymphocyte, the stimulated cell increased in size and possessed a greater plasma membrane surface area. Increase in cell size was the result of increases in the volumes of all measured subcellular compartments both in the nucleus and the cytoplasm. Heterogeneity of the stimulated cell population precludes firm conclusions regarding the significance of all these ultrastructural changes, though alterations in cell surface are discussed in the context of known biochemical differences accompanying blastogenesis.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 65
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 216 (1981), S. 557-568 
    ISSN: 1432-0878
    Keywords: Electron microscopy ; Neuroglia ; Silver impregnation ; Brain ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The silver-impregnation procedure of Tsujiyama is suitable for demonstration of all three classical types of neuroglial cells; in the present study it was used for electron microscopic identification of neuroglial cells in the brain of the cat. The aim of the present study was 1) to determine impregnated structural correlates of neuroglial cells at the light- and electron-microscopic levels, and 2) to determine whether the method of Tsujiyama is applicable for the electron microscopic identification of the single types of neuroglial cells. Silver deposits were observed over the cytoplasm and processes of astrocytes where numerous glial filaments were present. Oligodendrocytes and microglial cells may be precisely differentiated by use of Tsujiyama's silver impregnation method at the electron microscopic level due to the pattern of silver-deposition in these two basic types of cells. This silver-impregnation method combined with electron microscopy is thus suitable for a precise identification of neuroglial cells; the technique may prove to be very helpful in identification of such categories of neuroglial cells that encompass also the images of cells which cannot be classified by use of the standard methods.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 66
    Electronic Resource
    Electronic Resource
    Springer
    Protoplasma 119 (1984), S. 48-54 
    ISSN: 1615-6102
    Keywords: Electron microscopy ; Marine alga ; Membrane contrast ; Osmium-azole complexes ; X-ray microanalysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Addition of certain heterocyclic nitrogen-carbon compounds to standard osmium tetroxide solutions used as secondary fixative resulted in an enhanced general membrane contrast in cells of the marine algaEmiliania huxleyi (Lohmann) Kamptner. Ultrastructural cell morphology and the contrast distribution were compared between cells treated according to a standard secondary fixation procedure and cells post-fixed when above mentioned heterocyclic compounds were introduced; in both cases some of the ultrathin sections were post-stained. Different compounds were tested: 1,2,4-triazole (TRA), 3-amino-1,2,4-triazole (A-TRA), 5-amino-tetrazole (A-TEA) and 2,4,6-tri-amino-1,3,5-triazine (melamine). The results were interpreted to indicate the possible bonding types arising from interaction of the heterocyclic compounds with osmium tetroxide and with membrane constituents. Interpretations were partly inspired by considerations from coordination chemistry. All above tests which did not include post-staining of thin sections could be performed at alkaline pH, and consequently calcified structures were preserved. The enhanced osmium accumulation at membranes was verified with X-ray microanalysis, which also showed that in the cases where membranes were visibly contrasted, localization of probable sites of intracellular non-crystalline calcium was facilitated.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 67
    Electronic Resource
    Electronic Resource
    Springer
    Plant and soil 76 (1984), S. 127-137 
    ISSN: 1573-5036
    Keywords: Adenylate pool ; Biomass volume ; CO2 evolution ; Chitin ; DNA ; Electron microscopy ; Enzymes ; Fluorescent antibody ; Fumigation-respiration ; Fungi Histochemistry ; Imunofluorecence ; Jones-Mollison technique ; Microcosms ; Monoclonal antibodies ; Nitrogen ; Nutrients ; Oxygen consumption ; Phosphorus ; Phytotoxins ; Plate counts ; Rhizobium ; Rhizosphere ; Sulphur ; Xenobiotics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary There is an immense literature on biological and biochemical analyses of soils. Such analyses have revealed the enormous richness of species in soil and their vast range of metabolic potentials and ecological diversity. Accordingly, the approaches used to investigate the soil biota and its biochemistry usually have to be modified or adapted depending upon the purpose of the investigation. Studies of micro-organisms in the soil environment, are complicated because microbial cells are commonly attached to surfaces where they live side-by-side with other populations in consortia usually containing different morphological and physiological types. Such assemblages of organisms cannot be described quantitatively using cultural techniques, such as plate counts, which underestimate both cell numbers and viable biomass. The development of more powerful observational and staining techniques has improved our knowledge of the diverse morphological and biochemical composition of soil micro-communities. Such findings have been amplified at a grosser level by laboratory studies with multi-component systems (microcosms) to mimic field situations and to assess the range of biochemical potentials of microbial consortia. But despite notable advances in analytical methods we are still, with a few exceptions, unable to detect or identify those microorganisms which carry out specific biochemical transformations or determine whether particular cells are alive, dormant or dead at the time of observation. Considerable work has been done to define some of the fundamental ecological attributes of microbial assemblages in soil. Productive work on the metabolic activities of the soil microbiota, specially geochemical transformations of C, N, S and P, has been under way for more than a century. But only in more recent years have more sensitive and reproducible analytical methods become available to measure viable biomass in soil. This will enable some insight to be gained into the role that microbial biomass plays as a labile source and sink for plant nutrients.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 68
    Electronic Resource
    Electronic Resource
    Springer
    Plant and soil 76 (1984), S. 319-337 
    ISSN: 1573-5036
    Keywords: Aggregates ; Aluminium ; Bacterial mucilage ; Binding agents ; Calcium ; Cation bridges ; Complexing agents ; Dispersion ; Electron microscopy ; Electrophoretic mobility ; Fungal hyphae ; Glues Iron ; Management Periodate ; Polysaccharides ; Rhizosphere ; Roots ; Slaking
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The stability of pores and particles is essential for optimum growth of plants. Two categories of aggregates macro- (〉 250 μm) and micro- (〈250 μm) depend on organic matter for stability against disruptive forces caused by rapid wetting. Dispersion of clay particles from microaggregates is promoted by adsorption of complexing organic acids which increase the negative charge on clays. The acids are produced by plants, bacteria and fungi. However, the dispersibility of clay in microaggregates is offset by the binding action of polysaccharides, mainly mucilages produced by bacteria, but also by plant roots and fungal hyphae. The stability of microaggregates is also enhanced by multivalent cations which act as bridges between organic colloids and clays. Macroaggregates are enmeshed by plant roots, both living and decomposing, and are thus sensitive to management, and increase in number when grasses are grown and the soil is not disturbed. Lack of root growth,i.e. fallow, has the opposite effect. Various implications for management of soil structure are discussed.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 69
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 198 (1979), S. 119-127 
    ISSN: 1432-0878
    Keywords: Male hamster ; Harderian gland ; Castration ; Sexual dimorphism ; Porphyrin ; Testosterone ; Tubular clusters ; Membranous structures ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary A sexual dimorphism of the hamster Harderian gland at the ultrastructural level has been reported. The effect of testosterone on the fine structure of the gland from castrated male golden hamsters is reported here. Harderian glands from the following three groups of animals were examined at regular intervals up to 60 days after castration: (1) castrated; (2) castratedsham-injected, receiving 0.1 ml sesame oil per day; (3) castrated-testosterone injected, receiving 2mg testosterone propionate in 0.1 ml sesame oil per day. In groups 1 and 2, clusters of cylindrical tubules, typical of the male gland, decreased in number and disappeared almost completely 2 weeks after castration. Membranous structures, typical of the female gland, prevailed in these two groups throughout the remaining period of experiment. On the other hand, these changes were prevented in the group of castrated animals maintained on testosterone propionate. It is concluded that castration modified the ultrastructure of the male hamster Harderian gland toward the female type and that daily administration of testosterone propionate prevented this change.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 70
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 220 (1981), S. 153-161 
    ISSN: 1432-0878
    Keywords: Cytoplasmic transport ; Insect ovary ; Autoradiography ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ovarioles of Coccinella and Tenebrio are shown to be telotrophic — a characteristic normally associated with hemipterans rather than coleopterans. They possess an anterior region of trophic cells and a chain of oocytes. The trophic cells are connected with the latter by a series of nutritive tubes, and autoradiography has shown that RNA is transported along the tubes to the oocytes. However, the system in these beetles differs markedly from that of hemipterans in that the nutritive tubes do not contain an extensive complement of aligned microtubules. The significance of this to both the mechanism and the selectivity of transport is discussed.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 71
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 220 (1981), S. 201-212 
    ISSN: 1432-0878
    Keywords: Atretic oocyte ; Perca fluviatilis ; Histochemistry ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The regression of atretic oocytes in Perca fluviatilis was studied by histochemical, light and electron microscopic methods. The course of regression can be divided into three stages, the first two comprising the dissolution of the atretic oocyte and its phagocytosis by the granulosa cells of the follicular epithelium, and the third stage consisting of the dissolution of the granulosa cells themselves. The ultrastructure in all three stages shows only features related to phagocytosis and lysosome formation. In particular, there is no agranular endoplasmic reticulum formed within the phagocytically active granulosa cells, nor is there any 3β-hydroxysteroid dehydrogenase activity (3β-HSD). Large yellow-orange pigments, formed during the third stage of regression, are ascribed to a relative deficiency of lysosomes in lipid digestion, and do not result from a preceeding steroid-synthesising phase as in mammalian corpora lutea. Thus, the atretic oocyte of P. fluviatilis is considered not to give rise to a corpus luteum formation with endocrine function, but merely represents a degenerative structure.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 72
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 196 (1979), S. 541-543 
    ISSN: 1432-0878
    Keywords: Chromatophores ; Pigment organelles ; Organelle development ; Electron microscopy ; Phalangium opilio
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Observations of a number of vertebrate chromatophores have revealed the presence of more than one type of pigment organelles, suggesting that the different types are all derived from an equipotential organelle able to differentiate into any of the major pigment-containing organelles (Bagnara, 1972). Observations are presented concerning the occurrence of hybrid pigment inclusions, i.e., all kinds of intergrades between melanosomes, pterinosomes, and reflecting platelets in pigment cells of the daddy-long-legs. It therefore seems possible that pigment organelles in some invertebrates may also be derived from a common pluripotential primordial organelle.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 73
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 197 (1979), S. 79-94 
    ISSN: 1432-0878
    Keywords: Erythrophagocytosis ; Lysosomes ; Placenta (sheep) ; Acid phosphatase ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The breakdown of erythrocytes within the lysosomal apparatus of trophoblastic epithelial cells of the sheep placenta was studied at the ultrastructural level. Acid phosphatase activity could be demonstrated in the interspace between the erythrocyte membrane and the lysosomal membrane, but not inside ingested erythrocytes. The erythrocyte plasma membrane remained observable until the final stage of the breakdown process. Together with a peripheral layer of indigestible hemoglobin it might form a barrier for further penetration of lysosomal enzymes into the ingested erythrocyte. The hemoglobin of the erythrocyte is suggested to diffuse through the erythrocyte plasma membrane into the interspace between this membrane and the lysosomal membrane. Subsequently, the hemoglobin is digested in the interspace or in fragments pinched off from erythrocyte-containing lysosomes (=erythrolysosomes). The fragmentation of erythrolysosomes is considered to be the most efficient mechanism for the breakdown of red blood cells in the trophoblastic epithelium of the sheep placenta. The method of entry of hydrolytic enzymes into erythrocyte-containing phagosomes is discussed.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 74
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 197 (1979), S. 175-194 
    ISSN: 1432-0878
    Keywords: Retina ; Synapses ; Transmitter ; Electron microscopy ; Rabbit
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The recently discovered indoleamine-accumulating retinal neurons were studied electron microscopically after destruction of the dopaminergic retinal neurons and subsequent labeling with 5,6-dihydroxytryptamine. These observations confirm earlier fluorescence microscopical studies on the distribution of the indoleamine-accumulating neurons in the rabbit retina. Their perikarya are known to be located in the inner nuclear layer (INL) among the amacrine cell bodies. Their processes are found only in the inner plexiform layer (IPL), most of them in the innermost third part of that layer. The indoleamine-accumulating terminals are pre- and postsynaptic to bipolar neurons in the innermost sublayer of the IPL. Reciprocal synapses are probably the rule. The synaptic vesicles of indoleamine-accumulating synapses onto bipolar cells are arranged in “globular” clusters around a central electron dense, round body. A number of synapses formed by unlabeled amacrine neurons with postsynaptic indoleamine-accumulating elements were also detected. These synapses were mainly found in the outermost third of the IPL. Synaptic contacts between presynaptic indoleamine-accumulating neurons and postsynaptic unlabeled processes of amacrine cells are very rare.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 75
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 197 (1979), S. 281-294 
    ISSN: 1432-0878
    Keywords: Electron microscopy ; Light microscopy ; Gastric mucosa ; Reptilia ; Cytochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The gastric mucosa of a reptile, the lizard Tiliqua scincoides, has been examined by light and electron microscopy. The gastric pits lead into glands that are extensively coiled in the proximal stomach but become progressively shorter and straighter in the distal stomach. The following epithelial cell types have been identified: (i) Surface mucous cells (SMC) line the entire lumenal surface as well as the pits. They contain mucus granules that stain with periodic acid-Schiff and, like the granules of mammalian SMC, commonly contain an electron dense core that appears not to be mucus (periodic acid-chromic acid-silver methenamine nonreactive). (ii) Glandular mucous cells are present in glands throughout the mucosa. They are probably homologous with the mucous neck and antral gland cells of mammals; like SMC their mucus granules contain nonglycoprotein cores. (iii) Oxynticopeptic cells (OPC) are the predominant cell type in the proximal glands but become infrequent distally. Their fine structure resembles that of OPC in other nonmammalian vertebrates, with features like those of both parietal cells and zymogen cells of mammals, (iv) Endocrine cells of three different types have been identified. Two of these show close similarities to the EC and ECL cells of mammals.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 76
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 203 (1979), S. 173-180 
    ISSN: 1432-0878
    Keywords: Tissue culture ; Cardiac myocyte ; Heart ; T-tubes ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary T-tubes are among the last structural elements of the mammalian myocyte to develop in vivo. We were able to identify T-tubes in early cultures of neonatal rat myocytes. Ventricles were excised from 3- to 4-day-old neonatal rats, incubated overnight in cold trypsin, and treated with sequential changes of collagenase-hyaluronidase. Fractions of cells isolated in this manner were pooled and cultured in plastic petri dishes. In cells prepared for transmission electron microscopy, T-tubes were observed at the cell periphery of cultured myocytes, but were more difficult to identify as the cultures aged and became overgrown by fibroblasts. T-tubes were identified by virtue of their continuity with the sarcolemma, their relatively large diameter, and their regular entry at the level of the Z line. Even at optimal culture ages, T-tubes were not present in every myocyte. At the times T-tubes could be located, myocytes were beating and had begun to establish intercalated discs and gap junctions. The de novo formation of T-tubes in cultured myocytes of neonatal rat heart reflects a duplication of in vivo differentiation by the cultured myocyte. The appropriateness of cultured myocytes in the study of the development and physiology of the heart is emphasized by the in vitro formation of T-tubes.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 77
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 203 (1979), S. 209-221 
    ISSN: 1432-0878
    Keywords: Erythrophagocytosis ; Lysosomes ; Placenta (sheep) ; Acid phosphatase ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In trophoblastic epithelial cells of the sheep placenta the breakdown of erythrocytes within complex erythrolysosomes was studied at the ultrastructural level. It was found that the formation of complex erythrolysosomes containing from two to several erythrocytes as a result of fusion of erythrolysosomes within the epithelial cells was a common occurrence when the epithelial cells engulfed a large number of erythrocytes. The erythrocytes enclosed in complex erythrolysosomes appear to be either in the same or in different stages of hemolysis. In the process of breakdown of erythrocytes within complex erythrolysosomes five successive stages of hemolysis could be distinguished. Acid phosphatase activity was demonstrated in the complex erythrolysosomes and appeared to be located in the angular interspaces between the erythrocytes and the lysosomal membrane. The fragmentation of complex erythrolysosomes with formation of small hemoglobin-containing lysosomes also occurred. The fusion of erythrolysosomes with formation of complex erythrolysosomes can be considered as an additional mechanism in the process of erythrocyte breakdown in the epithelial cells of the sheep placenta.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 78
    ISSN: 1432-0878
    Keywords: Fat body ; Morphometry ; Metamorphosis ; Transplantation ; Calliphora ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Transplantation of fragments of the anterior fat body lobe of 4 day old feeding stage larvae into one day older hosts, which are at the end of feeding, leads to precocious induction of ultrastructural changes in the transplanted cells of the fat body. These changes include alterations in the mean relative and absolute areas of mitochondria, protein granules, lipid droplets and vacuoles. The extent of intracellular changes induced in the transplants depends on the physiological condition of the host. This confirms that alterations in the internal environment at termination of feeding induce premetamorphic changes in cells of the fat body.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 79
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 203 (1979), S. 301-309 
    ISSN: 1432-0878
    Keywords: Endocrine cells ; Calcitonin ; Ascidian (Styela clava) ; Immunofluorescence ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary A small group of granulated endocrine cells have been described in the endostylar region of the pharynx in Styela. These cells are argyrophilic and exhibit calcitonin-like immunofluorescence. Tests with antisera to other peptides all proved negative. Cells from animals exposed to elevated calcium levels showed a degree of degranulation. The possibility that these cells may represent ancestral ultimobranchial “C” cells is discussed.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 80
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 203 (1979), S. 487-492 
    ISSN: 1432-0878
    Keywords: Osteoclasts ; Endothelium ; Bone resorption ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The morphological relationship between the osteoclasts at the endosteal surface of two-week-old rabbit femurs and the endothelium of vascular channels of the bone marrow was examined. Light microscopy revealed that 85% of the osteoclasts make direct contact with the endothelial cells. The ultrastructure of this osteoclast-endothelium interface shows that the osteoclast has specialized processes which reach out towards the endothelial cells coming into close proximity with them. On rare occasions, specialized junctions between these processes and the endothelial cells are noted.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 81
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 203 (1979), S. 503-506 
    ISSN: 1432-0878
    Keywords: Muscle ; Disuse atrophy ; Insects ; Ultrastructure ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The changes which occur in the ultrastructure of the mesothoracic retractor unguis muscle of the cockroach Periplaneta americana as a result of disuse are described. Breakdown of myofibrils, sarcoplasmic reticulum, and mitochondria are all marked, this degeneration only being apparent 9 weeks after the operation.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 82
    ISSN: 1432-0878
    Keywords: Median eminence ; Hypophysis ; Rana temporaria ; Vasotocinergic fibres ; Mesotocinergic fibres ; Immunocytochemistry ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary With the use of the unlabelled antibody peroxidase-antiperoxidase complex (PAP) technique at the electron microscopic level, it was shown that both the internal and the external regions of the median eminence of the frog contain separate vasotocinergic and mesotocinergic nerve fibres. This observation confirms the results of previous immunocytochemical studies at the light microscopic level. The mean size of the neurohypophysial hormone-containing granules in the external region of the median eminence is significantly smaller than that of the neurohypophysial hormone-containing granules in the internal region of the median eminence. No significant difference could be found between the mean granule size of the vasotocinergic and mesotocinergic fibres of either the internal or the external region of the frog median eminence.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 83
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 204 (1979), S. 155-159 
    ISSN: 1432-0878
    Keywords: Nervus connectivus ; Periplaneta ; Synaptic contacts ; Iontophoresis ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The course of the Nervus connectivus (N.c.), its branches, and synaptic connections within the frontal ganglion (FG) were investigated electron microscopically after cobalt iontophoresis of the N.c. The subsequent treatment of ultrathin sections with Timm's method was found to be very suitable for identifying the smallest branches. In the neuropil, fibers of the N.c. form Gray-I-type synapses, but also dyads are abundant, whereby the N.c. fibers occur exclusively in postsynaptic position with neurosecretory fibers. The possible role of these relationships is discussed.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 84
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 204 (1979), S. 319-331 
    ISSN: 1432-0878
    Keywords: Median eminence ; Lamprey ; Regulation of pars distalis ; Fluorescence microscopy ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The proximal neurosecretory contact region (PNCR) of the lamprey, a homologue of the median eminence of tetrapods, was studied by light, fluorescence and electron microscopy. Paraldehyde fuchsin-positive neurosecretory fibers are seen mainly in the central part of the rostral subdivision of the PNCR. The Falck-Hillarp technique reveals a weak, mainly diffuse yellow-green fluorescence in the PNCR. The ultrastructure of the tanycyte layer of the PNCR is very similar to that in the neurohypophysis of the same species, although the funnel-shaped protrusions of the third ventricle in the rostral part of the PNCR are more frequent than in the neurohypophysis. Peptidergic A1 and A2 neurosecretory fibers are characterized by neurosecretory granules of 120– 200 nm and 100–150 nm in diameter, respectively. Monoaminergic B type fibers contain granules 80–100 nm in diameter. Neurosecretory terminals and the vascular endfeet of tanycytes make contact with the basement membrane of the avascular connective tissue layer separating the PNCR from the hypophysial pars distalis. It is suggested that both peptide and monoamine neurohormones diffuse through the thick connective tissue septa into the underlying blood vessels which supply the pars distalis and thus affect the function of its glandular cells.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 85
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 214 (1981), S. 81-87 
    ISSN: 1432-0878
    Keywords: Sperm-host glands ; Spermatozoa ; Fowl ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The disintegration of spermatozoa in the infundibular sperm-host glands of the fowl was investigated by electron microscopy. After the 15th day following artificial insemination, secretory granules in the epithelial cells of the sperm-host glands increase in number and size, and subsequently the contents of the granules are released into the glandular lumen, so that the electron density of the lumen increases. At this stage, spermatozoa stored in the glands begin to undergo degenerative changes starting from the head. The heads become distended and chromatin of the nucleus begins to disperse as small masses, simultaneously with the destruction of the acrosome. As the dispersion of chromatin progresses, mitochondria of the middle piece become distended and irregular in shape, and then disintegrate. At the last stage, most of the organelles have disappeared, but the fibrous sheath and axial-filament complex are still identified.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 86
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 214 (1981), S. 89-95 
    ISSN: 1432-0878
    Keywords: Spermatozoa ; Vitelline membrane ; Macrophage ; Fowl ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The fate of spermatozoa that do not participate in fertilization was investigated by electron microscopy. After artificial insemination, we observed several spermatozoa between the fibers of the outer layer of the vitelline membrane of the ovum. One or more spermatozoa were also found in a phagocytic vesicle of macrophages located in the intercellular space of the mucosal epithelium of the infundibulum or in the outer layer of the vitelline membrane. From these observations, we assume that the superfluous spermatozoa in the lumen of the anterior part of the oviduct might be removed by inclusion into the outer layer of the vitelline membrane and by phagocytosis by macrophages.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 87
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 215 (1981), S. 133-142 
    ISSN: 1432-0878
    Keywords: Rat fetus ; Hepatocyte differentiation ; Ultrastructure ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Rat hepatocyte differentiation between day 12 and 19 of fetal life was studied by electron microscopy. The cytoplasmic structures involved in synthetic and secretory function, i.e., rough endoplasmic reticulum and Golgi apparatus, appear to be the first to differentiate, and their development is probably related to the secretion of different kinds of plasma proteins. The cytoplasmic organelles involved in other hepatic functions develop later: lysosomes from day 15, peroxysomes, glycogen rosettes and smooth endoplasmic reticulum still later. However, the morphological differentiation of bile canaliculi begins from day 12.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 88
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 215 (1981), S. 223-247 
    ISSN: 1432-0878
    Keywords: Active transport ; Supravital microscopy ; Electron microscopy ; Preparative cell shrinkage ; Frog gallbladder
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Morphologic findings of widely dilated intercellular spaces in fluid transporting epithelia have been claimed as evidence for the existence of an epithelial compartment in which the coupling between solute and water fluxes takes place. The validity of using epithelial geometry in sectioned material as an argument can be questioned. The present report describes the morphological appearance of frog gallbladder epithelium — normal and ouabain-treated — in the living state in vitro and after fixation, dehydration and embedding. Gallbladder segments were photographed in the living state and at the end of each step of the preparative procedure. Direct observations of whole-mounted gallbladder segments were carried out, taking advantage of the possibility of optical sectioning and high resolution by Nomarski-microscopy. The same specimens were then sectioned and examined by conventional light and electron microscopy. The observations were quantitated and showed that the epithelial cells of normal and ouabain-treated gallbladders experienced an average linear shrinkage down to 70% of their length in Ringer's solution, which corresponds to a volume shrinkage down to 35%. Moreover, dilated lateral intercellular spaces appeared during the dehydration and embedding procedure in normal but only very moderately or not at all in ouabain-treated gallbladder specimens.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 89
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 219 (1981), S. 69-83 
    ISSN: 1432-0878
    Keywords: Satellite cells ; Cardiac muscle ; Decapod crustaceans ; Distribution ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The structure and distribution of satellite cells of cardiac muscles were examined in twenty-one species of animals chosen from each tribe within the order Decapoda (Arthropoda, Crustacea). The satellite cells were found in all animals observed. Most of them are morphologically identical with those described in different striated muscles of other species, but some cells have unusual features. The decapod satellite cell occasionally lies right over the region corresponding to the intercalated disc between the apposed cardiac muscle cells. The cell sends cytoplasmic processes into the adjacent muscle cells, enabling the plasma membrane to make close contact with the cleft opening of the intercalated disc, and with the myofibril at the level of the Z-line. Another characteristic feature is the presence of “paired” cells. Such cells are clearly separated from each other over most of the contact area by the respective plasma membranes, which are smooth in appearance and devoid of specialized regions. The significance of the presence of satellite cells in decapod cardiac muscle and its possible role are discussed and compared with those described for other species.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 90
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 219 (1981), S. 313-325 
    ISSN: 1432-0878
    Keywords: Oligodendroglia ; Cell surface antigens ; Electron microscopy ; Immunoperoxidase ; Monoclonal antibodies
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Monoclonal antibodies to cell-surface antigens of oligodendrocytes (Sommer and Schachner 1980; Schachner et al. 1980) were used to identify this cell type by immuno-electron microscopy in monolayer cultures of fetal and early postnatal mouse cerebellum. The ultrastructural features of antigen-positive cells confirm that they are immature and mature oligodendrocytes, but not neurons, astrocytes or fibroblasts or fibroblast-like cells. Type I oligodendrocytes are the immature ones with a relatively large amount of moderately electron-lucent cytoplasm, clusters of ribosomes and complex networks of rough endoplasmic reticulum. Large numbers of mitochondria and microtubules, but not intermediate-sized filaments are seen in these cells. They comprise more than 90% of all 0-antigen-positive cells. Type II cells comprise only approximately 5% of all 0-antigen-positive cells. They are characterized by a limited amount of electron-dense cytoplasm, which appears more compact and granular than in type I cells. The rough endoplasmic reticulum is distributed evenly throughout the cytoplasm. Microtubules and mitochondria are present, but more difficult to distinguish due to the compactness of the cytoplasm. Type II cells display the more mature ultrastructural features of oligodendrocytes.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 91
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 219 (1981), S. 433-436 
    ISSN: 1432-0878
    Keywords: Electron microscopy ; Frog ; Cutaneus pectoris muscle ; Nerve ; Muscle spindle
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Three muscle fibers were identified by electron microscopy within a nerve of a frog muscle. They resembled extrafusal muscle fibers but were located in an endoneurial rather than in an endomysial compartment. To call these endoneurial muscle fibers the obvious continuation of extrafusal fibers of a muscle spindle is certainly unwarranted; to label these fibers ectopic and to let the matter rest there is probably an understatement of sorts.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 92
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 220 (1981), S. 435-438 
    ISSN: 1432-0878
    Keywords: Haemocyanin ; Branchial gland ; Electron microscopy ; Eledone moschata ; Cephalopoda
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Polymerized haemocyanin molecules have been identified as rings, about 25 nm in diameter, forming linear arrays within cytoplasmic vesicles, close to the nucleus. They were observed by transmission electron microscopy in the polygonal cells of the branchial gland of Eledone moschata Lamarck. These observations confirm previous data suggesting that haemocyanin is synthetized in the branchial gland cells of Octopoda.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 93
    ISSN: 1432-0878
    Keywords: Neurosecretory granules (Insects) ; Ionophores ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The antibiotic ionophores Br-X-537A and A-23187 alter the ultrastructure of neurohaemal tissue on the transverse nerve of the stick insect, Carausius morosus. Br-X-537A induces dramatic changes in the ultrastructural appearance of all three types of neurosecretory fibres present in the neurohaemal tissue. The neurosecretory granules become more electron-lucent and the mitochondria become more electron-opaque. The bounding membrane of the granules is frequently ruptured. A-23187, on the other hand, has no effect on two of the three types of fibres, but does produce an increase in the number of exocytotic profiles in the third. The two ionophores therefore have different effects on the same tissue. The results are discussed in the light of previous work with the use of these ionophores.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 94
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 197 (1979), S. 257-262 
    ISSN: 1432-0878
    Keywords: Centrifugal fibers ; Olfactory bulb ; Goldfish ; Degenerating synapses ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The terminals of centrifugal fibers to the olfactory bulbs of goldfish were studied by electron microscopy after transection of the medial, lateral or entire olfactory tract. The centrifugal fibers originate in the telencephalic hemisphere, pass through both the medial and the lateral olfactory tract, and form synaptic contacts with dendrites in the granule cell layer.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 95
    ISSN: 1432-0878
    Keywords: Monocytes ; Macrophages ; Epithelioid cells ; Multinucleated giant cells ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The morphological changes occurring in monocytes during their differentiation into macrophages, epithelioid cells, Langhans-type giant cells, and foreign-body-type giant cells were investigated in foreign-body granulomas induced by subcutaneous implantation of pieces of Melinex plastic. Analysis based on Adams's (1974) criteria for discrimination between the several types of cell of the monocyte line, showed that each type has a characteristic type of granule. Primary and secondary granules, numerous in the Golgi area of monocytes were generally found close to the cell membrane and decreased in number in maturing macrophages. This was accompanied by an increase in the number of microtubules. Mature macrophages show numerous characteristic macrophage granules, which are round (average diameter: 280 nm) and have a halo between the limiting membrane and granular matrix. Mature epithelioid cells have characteristic epithelioid cell granules, and multinucleated giant cells a heterogeneous population of granules. Fusing macrophages generally have their Golgi areas facing each other, and also show a reduced thickness of the cell coat. The morphology of the multinucleated giant cell is closely related to the number of nuclei present. In Langhans-type giant cells, which generally have two to ten nuclei, a giant centrosphere with numerous aggregated centrioles is found. In transition forms between Langhans-type and foreign-body-type giant cells, which generally contain 10–30 nuclei, the centrioles show less aggregation. In the foreign-body-type giant cells, which generally have more than 30 nuclei, centrioles are virtually absent and never aggregated. These differences between the Langhans-type giant cells, the foreign-body-type giant cells, and the transition forms, support our previous finding that Langhans-type giant cells are the precursors of foreign-body-type giant cells.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 96
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 198 (1979), S. 79-93 
    ISSN: 1432-0878
    Keywords: Fat body ; Calliphora ; Metamorphosis ; Morphometry ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In the fat body of Calliphora a drastic reorganization of the cell structure, which is related to premetamorphic functional changes, can be observed during the 3rd larval stage of development. These changes include an accumulation of protein storage granules, a decrease in the relative volume of the mitochondria and the surface area of endoplasmic reticulum membrane, and the disappearance of vacuoles. “Absolute” values obtained for organelle areas and membrane perimeters confirm the assumption that large numbers of organelles are eliminated by autophagic activity prior to the pupation period. A temporary restoration of the endoplasmic reticulum is found immediately before pupariation. Large variations in organelle density were found between individual fat cells and between the nuclear, mid- and peripheral regions of the cytoplasm.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 97
    ISSN: 1432-0878
    Keywords: Endogenous peroxidase ; Trachea ; Lung ; Electron microscopy ; Guinea pig
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Endogenous peroxidase activity was demonstrated by cytochemistry in mucous cells of the submucosal glands and tracheobronchial epithelium of guinea pigs. It is localized in the nuclear envelope, in cisternae of rough endoplasmic reticulum, and in secretory granules. It was not seen in Golgi saccules or in the airway lumen. By contrast, all epithelial cells within the lung including mucous (goblet) cells lack activity. Reaction product is also absent from alveolar macrophages and mast cells. The appearance of peroxidase in mucous cells is age-related. No activity was seen at 1.5ms of age. A few mucous cells were positive at 2.5 and 3 ms while the proportion of positive cells increased substantially up to 7 ms. Thus, the age of guinea pigs in HRP transport studies must receive careful consideration in order to avoid misinterpretation of results. The function of mucous cell peroxidase is unknown. The results of this study suggest that it is secreted. Whether it plays a significant role in lung defense through its well documented anti-infectious properties remains to be determined.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 98
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 214 (1981), S. 443-448 
    ISSN: 1432-0878
    Keywords: Chitin synthesis ; Electron microscopy ; Acari ; Tetranychus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Two chitin synthesising systems in Tetranychus urticae are described: one chitosomal system located in the oocytes where spatial and temporal distances are large, and one membrane bound system located in the hypodermis. Similarity of mechanisms of chitin synthesis in animals and plants is suggested.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 99
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 214 (1981), S. 501-518 
    ISSN: 1432-0878
    Keywords: Placenta (sheep) ; Cell phagocytosis ; Hemoglobin-derived pigments ; Residual bodies ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In trophoblastic epithelial cells of the sheep placenta the final stages of erythrocyte breakdown within the lysosomal apparatus were studied at the ultrastructural level. As a result of hemoglobin digestion lysosomes containing hemoglobin-derived pigments (HDP) were formed. The HDP-lysosomes were acid phosphatase-positive, highly electron-dense bodies of round to irregular shape containing whorled membranous formations. The accumulation of these lysosomes in epithelial cells led to fusion resulting in the formation of conglomerates. At the end of the gestation period the amount of HD Plysosomes and their conglomerates markedly increased. In addition to erythrocytes the trophoblastic epithelial cells in the erythrophagocytic regions phagocytosed maternal leukocytes and neighbouring epithelial cells and giant cells. By gradual accumulation of HDP-lysosomes and remnants of phagocytosed cells, highly electron-dense acid phosphatase-positive residual bodies of variable appearance were formed within the epithelial cells. At the end of pregnancy the spaces between juxtaposed villi of the trophoblastic epithelium in the erythrophagocytic zones were occluded by apposition of the epithelial cells. In these occluded regions an increase in highly electron-dense large-sized residual bodies (15–22 μm of dimension) occurred as a result of multiple cell phagocytosis in combination with fusion. In these residual bodies the numerous incorporated HDP-lysosomes and the remnants of phagocytosed cells could still be recognized.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 100
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 220 (1981), S. 555-559 
    ISSN: 1432-0878
    Keywords: Disaccharidases ; Intestinal brush-border membranes ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The intestinal disaccharidases, lactase, sucrase-isomaltase complex, and glucoamylase are proteins intimately associated with the brush-border membrane of the epithelial cell. These three enzyme activities are found in the intestine of the adult rat; lactase and glucoamylase activities are primarily associated with the intestine of the infant rat. Only glucoamylase and isomaltase activities are detected in the intestine of the California sea lion, Zalophus californianus. The activities of these enzymes are detected only in villus cells, and not in crypt cells. We have carried out electron microscopic studies of negatively stained brush-border preparations of intestinal crypt and villus cells; from the intestine of the 10-day-old rat and from that of the California sea lion. The density of the knob-like structures protruding from the brush-border membranes was not significantly different in any of these preparations. The diameter of the knobs on the preparations from crypt cells was smaller than the diameters of the knobs found on membranes prepared from the other sources. These data are discussed in terms of the relationship between the presence of knob structures and disaccharidase activities associated with the brush-border membranes.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...