Your email was sent successfully. Check your inbox.

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

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    ISSN: 0741-0581
    Keywords: Vascular casts ; Scanning electron microscopy ; Vascular anatomy ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: Corrosion casts provide three dimensional replicas that can be examined readily by scanning electron microscopy (SEM). They are prepared by filling vascular networks with polymerizing plastic and then digesting away the tissue. As based on our studies of ocular vessels, this report describes the vascular anatomy, as well as the artifacts, that are encountered during SEM studies of such preparations.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 2
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 60 (1937), S. 489-519 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Plethodon cinereus is favorable for a study of the history of the germ line. The germ cells are large, while the gonads are small and show an almost diagrammatic structure. Germ cell degeneration is not extensive during ontogeny. As long as all the germ cells contain yolk during development, these cells are derived solely from germ cells. In Plethodon, yolk lasts in all germ celis through sex differentiation. A comparison of the number of mitoses necessary for the primordial germ cells to produce the numbers of germ cells in gonads where every germ cell contains yolk, with the mitoses necessary for the primordial cells to produce the adult complements of germ cells, shows that at least 72% of the increase of germ cells can be followed by yolk. A cytological study from the embryo through the adult sexual cycle gave no evidence that somiatic cells ever transform into germ cells. Mitoses are abundant in the testes of salamanders starved 4 months. This fact together with a statistical study on the adult male sexual cycle indicates that the germ cells present in the testis do not need to be augmented by transformed somatic cells. It is concluded that in Plethodon germ cells alone give rise to germ cells, and that the germ line is continuous.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 3
    ISSN: 0730-2312
    Keywords: glycans ; cell recognition ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: A proteoglycan-like aggregation factor from the marine spongeMicrociona prolifera (MAF) mediates cell-cell recognition via a cell-binding and a self-association domain. After repetitive and prolonged treatment of MAF with glycopeptide-N-glycosidase (PNGase) the specific binding of MAF to homotypic cells was decreased by 72%. Polyacrylamide gel electrophoresis and gel filtration analysis of such PNGase digests showed that: (1) the enzyme released a single glycan type of Mr = 6 × 1032 (G-6) from MAF, (2) 1 mole of MAF contains at least 830 moles of N-linked chains of G-6 glycan. The correlation between the loss of the binding activity of MAF and the extent of the release of the repetitive G-6 polysaccharide strongly suggests its involvement in MAF-cell association via highly polyvalent interactions.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 4
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Injections of India ink colored blood, latex, and plastic followed by study of corrosion casts and dissections were used to determine the interconnections of the vertebral venous system and pulmonary circulation in the chicken. Multiple, minute connections are found to the intercostal veins, small mesenteric veins and others connected to the vertebral venous system. Thus, blood can flow in quantities between the vertebral venous system and the pulmonary circulation depending upon pressure gradients.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 5
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Bone cells obtained by digestion of fetal mouse or chicken calvaria were tested for their ability to form or resorb bone in vitro. The isolated cells were precultured for 6 days and subsequently cocultured for 11 days with periosteum-free noninvaded fetal mouse long bone rudiments. Bone formation and resorption during coculture were evaluated by histology and 45Ca release from prelabeled bones. The calvarial origin of cells in cocultures was traced by labeling the cells with 3H-thymidine before coculture, followed by autoradiography.Many osteoblasts and osteoclasts as well as fibroblasts developed from mouse periosteal cells released late in the sequential digestion procedure and previously denoted as “osteoblastlike” (BL). No or few osteoblasts and osteoclasts but many fibroblasts developed from early released cell fractions that have previously been denoted as “osteoclastlike” (CL).Only osteoblasts and fibroblasts but not osteoclasts developed from chicken calvarial cell fractions. The osteoblasts developed primarily from cell fractions from the inner layer of the periosteum, previously denoted as “osteoblastlike” (OB). Cells obtained from the outer layer of the periosteum (PF) gave rise mainly to fibroblasts.These studies show that osteoblast and osteoclast precursor cells are maintained in monolayer cultures of periosteal cell fractions. However, sequential digestion of mouse calvaria does not lead to separation of the two types of bone cells. Rather, osteoclast and osteoblast precursors are released jointly, from the periosteal cell layers closest to the bone surface. In the chicken cell fractions osteoclast precursors are absent after preculture, resulting in a more homogeneous population of osteoblast and fibroblast but not osteoclast precursors.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 6
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A study of the male sexual cycles of five species of Plethodontid salamanders indicated that annually occurring non-functional regions at the anterior and posterior ends of the testis are associated with the two types of germ cell degeneration: (1) extensive degeneration of secondary spermatogonia in the anterior region; (2) complete degeneration in the posterior region, beginning with the young spermatocytes, of all germ cells except the primary spermatogonia. The improbability of the posterior degenerations being caused by a suggested climatic action is discussed. The presence only in urodeles of a caudo-cephalic polarity of spermatogenesis over the length of the testis and of these degenerations seem more than a coincidence. The abortive spermatogenetic cycle of immature males shows a caudo-cephalic sequence and the stages of degeneration that are identical with the adult. Inanition experiments indicate that the formation of secondary spermatogonia and the ability to form sperm are not synonomous. It is suggested, therefore, that normally more of the testis is activated than can be brought to a successful spermatogenesis. Since spermatogenesis moves caudo-cephalically, the posterior end will be left outside the functional zone, and consequently the cells degenerate. The anterior degenerations and the failure of anterior end of the testis to be involved in spermatogenesis, mark the anterior regulation of the spermatogenetic process. Degenerations can be regarded as the by-product of the regulation of overactivation.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 7
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 8
    ISSN: 0730-2312
    Keywords: detergents ; noradrenaline secretion ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Membrane events in exocytosis were studied by examining the effect of different detergents on the K+-stimulated release of noradrenaline in the secretory cell line PC 12. The nonionic detergent Triton X-100 and the cationic detergent cetyltrimethylammonium bromide (CTAB) inhibit the noradrenaline release evoked by 55 mM K+ by 50% at very low concentrations (30 μM and 10 μM, respectively). These values are tenfold lower than the critical micellar concentrations (CMC). No such effect was seen with the anionic detergent sodium dodecyl sulphate (NaDodSO4).The inhibitory effect of 30 μM Triton X-100 is reversible, and the recovery from inhibition correlates with the loss of detergent from the cells as demonstrated by binding studies using [3H]Triton X-100. The possible relationship between this inhibition of secretion and the structural properties of the detergent was investigated. The inhibition in the presence of purified Triton X-100 subfractions turned out to be a function of the length odemonstrated by binding studies using [3H]Triton X-100. The possible relationship between this inhibition of secretion and the structural properties of the detergent was investigated. The inhibition in the presence of purified Triton X-100 subfractions turned out to be a function of the length of the oligometric ethyleneglycol chain (C6 to C26). The maximal effect was observed for Triton X-100 molecules having a chain length of 16 carbon atoms, which can penetrate just half of the lipid bilayer of the membrane. Additionally, the phase transition at 13-14°C observed in an Arrhenius plot of noradrenaline release in stimulated cells was abolished.In the presence of 30 μM Triton X-100, 22Na+ uptake, 86Rb+ release, and 45Ca2+ uptake were reduced by 50-60%. These data suggest that the site of action of Triton X-100 is at the level of altering the movement of ions in PC 12 cells during the stimulatory phase of secretion.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 9
    Electronic Resource
    Electronic Resource
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 50 (1992), S. 237-244 
    ISSN: 0730-2312
    Keywords: cytoskeleton ; phosphorylation ; platelet ; vinculin ; protein kinase C ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Vinculin is a cytoskeletal protein believed to be involved in linking microfilaments to the cell membrane. it is a substrate for the Ca2+ - and phospholipid-dependent protein kinase C. We show here that when human platelets attach and spread on a solid surface, the α isoforms of vinculin become phosphorylated at serine and/or threonine residues. Phosphorylation is dependent on adhesion to a surface, since suspended, unattached platelets can produce filopodia but no phosphorylation of vinculin. Phosphorylation is also dependent on actin polymerization, as it does not occur when platelets had been pretreated with cytochalasin B. Most likely, protien kinase C is responsible for the phosphorylation of vinculin, since phosphorylation also occurs when platelets are treated with a phorbol ester, which activates protein kinase C, and is blocked by treatment with a staurosporine derivative which inhibits this enzyme. These results suggest that phosphorylation plays a role in anchoring vinculin at sites of microfilament-membrane interaction. © 1992 Wiley-Liss, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 10
    ISSN: 0730-2312
    Keywords: proteoglycan secretion ; aggregation ; AP ; SDS-PAGE ; sulfate deprived cells ; cell motility ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Sulfate is an important component relating to normal proteoglycan secretion and normal motility in the marine sponge, Microciona prolifera. The following alterations were observed in sponge cells when sulfate free artificial sea water was used as the suspension medium: (1) impairment of aggregation, (2) loss of cell movements, (3) a marked reduction in the secretion of the adhesion proteoglycan (AP). Reversal of this effect occurred if sulfate depleted cells were again rotated in sulfate containing artificial sea water. Motility and reaggregation of sulfate deprived cells could be completely restored by purified AP, but only if cells were first pre-conditioned in normal sea water. Comparisons of 35SO42- uptake between normal and sulfate deprived cells which had been treated to reduce preformed secretions showed a marked increase in 35SO42- uptake and incorporation which could be greatly augmented in the presence of Ca2+/Mg2+. Excessive retention of AP in sulfate starved cells demonstrated by immunostaining suggested that AP secretion and cellular motility may be controlled by a sulfate dependent secretogogue or that undersulfated AP itself had developed a secretory defect. SDS-PAGE of Triton treated cellular extracts demonstrated a 116 kDa 35SO42- sulfated band which co-migrated with AP, but only in extracts derived from sulfate starved cells. Western blots prepared from such extracts incubated in the presence of a monoclonal anti-band 3 antibody demonstrated labelling of a single 97 kDa band only in material from sulfate deprived cells. The absence of this component in normal cell extracts indicated that this protein may be involved in facilitated sulfate transport. This study lends support to a heretofore unrecognized role for sulfate in cell motility and secretion.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...