Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

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

Proceed reservation?

Export
Filter
  • Articles: DFG German National Licenses  (38)
  • 1
    Electronic Resource
    Electronic Resource
    Localization of epidermal growth factor receptors in cells of the enamel organ of the rat incisor
    Amsterdam : Elsevier
    Developmental Biology 148 (1991), S. 590-601 
    Details
    ISSN: 0012-1606
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/0012-1606(91)90276-9
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Immunolocalization of the Cation-Independent Mannose 6-Phosphate Receptor and Cathepsin B in the Enamel Organ and Alveolar Bone of the Rat Incisor (1996)
    Springer
    Calcified tissue international 59 (1996), S. 192-199 
    Details
    ISSN: 1432-0827
    Keywords: Key words: Mannose 6-phosphate receptor — Cathepsin B — Ameloblast — Immunocytochemistry.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract. In order to examine our hypothesis that maturation ameloblasts could degrade the enamel matrix in a manner analogous to bone resorption mediated by osteoclasts, we have assessed the distribution of lysosomal enzymes in the enamel organ by immunolocalizing the cation-inindependent mannose 6-phosphate receptor (MPR) and the lysosomal enzyme cathepsin B at all stages of amelogenesis. Secretory ameloblasts showed strong immunoreactivity for MPR in the supranuclear Golgi region and in the cytoplasm between the Golgi region and the distal junctional complexes. However, cathepsin B immunoreactivity was mainly seen in the distal portion of Tomes' process, which was unreactive for MPR immunogenicity. In maturation ameloblasts, the MPR was observed on the ruffled border of the ruffle-ended ameloblast (RA) but not on the distal cell membrane of the smooth-ended ameloblast (SA), although both cell types demonstrated strong immunoreactivity for MPR in the Golgi region. Immunoreactive cathepsin B was seen at the distal ends of both RA and SA. It is postulated that the nascent lysosomal enzymes bind to the mannose 6-phosphate receptors which target them not only to intracellular lysosomes, but also to the ruffled border of maturation ameloblasts where these enzymes are secreted into the enamel. Since MPR and lysosomal enzymes were also detected on the ruffled border of osteoclasts (Ocl) adjacent to alveolar bone, our immunocytochemical approach provides strong evidence for a similarity between the maturation process in enamel, as mediated by the ruffle-ended maturation ameloblasts, and bone resorption mediated by osteoclasts. This study has established that a common mechanism, based on MPR-targeted lysosomal secretion and matrix degradation, is basic to the maturation process involved in calcified tissues as different as bone and enamel.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002239900108
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Modification of the enamel maturation pattern by vinblastine as revealed by glyoxal bis(2-hydroxyanil) staining and 45calcium radioautography (1986)
    Springer
    Histochemistry and cell biology 86 (1986), S. 141-145 
    Details
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Patterns characteristic of enamel maturation can be visualized at the surface of the rat incisor by staining with glyoxal bis(2-hydroxyanil) (GBHA) and radioautography following 45calcium injection. In this study, the effects of vinblastine on enamel maturation were monitored by these two methods. At 4 h after injection of vinblastine, the darkly-stained GBHA bands had widened incisally into the interband regions when compared to normal, control teeth. Radioautography at 5 min after calcium injection in vinblastine-treated animals (4 h) showed a modified maturation pattern of weaker labeling and less distinct banding. At 8 h after vinblastine injection, most of the enamel stained uniformly with GBHA, and bands and interband regions could not be resolved. Radioautography at 5 min after calcium injection showed that the 8 h vinblastine treatment removed the banding pattern, leaving only a weakly-labeled area. Vinblastine is known to destroy and prevent the formation and turnover of microtubules, and hence the formation of ruffled borders of ruffle-ended ameloblasts (Akita et al. 1983). The concomitant decrease in calcium incorporation implies that events taking place in relation to the ruffled border may affect calcium exchange or accretion within the enamel.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00493379
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Multinucleate ameloblasts in the rat incisor (1977)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 188 (1977), S. 407-415 
    Details
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Cytological examination of the rat incisor enamel organ with the light and electron microscope revealed a small number of ameloblasts which contained two and sometimes three or more nuclei per cell. A multinucleate ameloblast usually contained two vertically apposed nuclei situated near the base of the cell. A narrow cytoplasmic band was interposed between adjacent nuclear envelopes. The apical nucleus was often the more elongated of the two nuclei and it fitted a convexity or a concavity within the more basally positioned nucleus. In serial sections examined with the electron microscope no connections were observed between the nuclei. In animals injected with 3H-thymidine instances of multinucleate ameloblasts were found within the advancing front of labeling where only one of the nuclei contained label. Finally, quantitative analysis by nuclear counting established that multinucleate ameloblasts were 60 times more frequent within the maturation zone as in the secretory zone of amelogenesis. As well, the numbers of multinucleate ameloblasts increased progressively in the course of the maturation stage. It was concluded that multinucleate ameloblasts increase with cell age and likely arise by the process of cell fusion.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1091880402
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Quantitative analysis of rough endoplasmic reticulum approaches to the cell membrane in the secretory ameloblast of the rat incisor (1984)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 209 (1984), S. 289-295 
    Details
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The distribution of approaches of rough endoplasmic reticulum to the cell membrane within the supranuclear region of the secretory ameloblast of the rat incisor was quantitated using a Zeiss MOP-3. In ameloblasts cut in cross section, most of these approaches appear as circular profiles representing cross sections of elongated cisternae, which are aligned parallel to the long axis of the cell. Because of their position, orientation, and distribution of ribosomes, these approaches were consistent with the appearance of subsurface cisternae. Using cross-sectioned ameloblasts, the lengths of apposed plasma membranes either between or within rows of cells were measured from electron micrographs. Along these lengths, matched approaches of rough endoplasmic reticulum from opposite sides of the apposed plasma membranes were counted. Approaches from either side that were unmatched were also counted. Thirteen percent of the approaches were matched between rows of ameloblasts, and 13.5% of the approaches were matched within rows, demonstrating no significant difference between the two sites. Furthermore, mathematical analysis showed that the theoretical probability of two approaches coinciding is 17%. The experimental values are not statistically different from the theoretical probability, and it is concluded that the matching of rough endoplasmic reticulum approaches to the plasma membrane, or subsurface cisternae, occurs at random.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1092090305
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    The fine structure of secretory ameloblasts in rat incisors (1968)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 161 (1968), S. 211-229 
    Details
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The fine structure of the ameloblasts which secrete the inner enamel matrix in rat incisors was described using light and electron microscopy. The tissue was fixed by perfusion with 2.5% glutaraldehyde and gently decalcified in isotonic EDTA.The ameloblasts are tall cells forming a simple columnar epithelium. The base is adjacent to the stratum intermedium and the apex (Tomes' process) extends into newly-formed enamel. The infranuclear zone is divided by the basal cell web into a small basal bulge adjacent to the stratum intermedium, and a larger compartment containing most of the cell's mitochondria. The supranuclear zone contains the rough endoplasmic reticulum and the Golgi apparatus. The rough endoplasmic reticulum predominates in the proximal and distal regions of this zone where it occupies most of the cell width. In the intermediate region, the rough endoplasmic reticulum surrounds a central tubule-shaped Golgi apparatus, the tubule wall being made up of flattened saccules. The Golgi region of ameloblasts is associated with coated vesicles, two types of granules (light and dark) which may be lysosomes, and a characteristic dense content granule shown to be the enamel precursor (0.16 μ diameter).The supranuclear zone is separated from Tomes' process by the apical cell web. Tomes' process is devoid of endoplasmic reticulum and Golgi material, but contains numerous dense content granules as well as microtubules and coated vesicles. The amorphous dense content granules are the precursors of the highly orientated fibrous enamel matrix. The proximity of the process to the fibrous enamel suggests that it is involved in orientation of these fibrils. Since bundles of fibrils constitute rods, the process would seem also to be involved in enamel rod orientation.
    Additional Material: 19 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1091610207
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Cellular renewal in the enamel organ and the odontoblast layer of the rat incisor as followed by radioautography using 3H-thymidine (1975)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 183 (1975), S. 523-561 
    Details
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Renewal of the cell populations of the incisor was studied in 100 gm male rats injected with a single dose of 3H-thymidine and sacrificed at various times from one hour to 32 days after injection. Radioautographs showed that a cohort of labeled cells within the enamel organ, odontoblast layer, and pulp was carried passively with the erupting incisor from the apical end toward the gingival margin where the life cycle of these cells was terminated. Labeled cells in the upper and lower incisor, although traversing different absolute lengths, were found in approximately the same functional stage of their life cycle at similar times after the injection. Thus, by one and one-half days labeled ameloblasts began inner enamel secretion. By 32 days labeled ameloblasts had traversed the entire maturation zone and were located at the gingival margin. Labeled odontoblasts followed closely the movement of labeled ameloblast. The mean rate of ameloblast migration was 567 μm/day on the upper incisor and 651 μm/day on the lower. For the odontoblasts this rate was 500 μm/day (upper) and 631 μm/day (lower). Finally, it was found that as the rat aged, the duration of the life cycle for epithelial and pulp cell populations of the incisor increased because of growth within the longitudinal axis of the tooth. It was concluded that the apical end of the incisor literally “grows backward” in the bony socket, and hence, the duration of the life cycle becomes greater simply because it takes cells longer to physically reach the gingival margin.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1091830405
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Quantitative analysis of cell turnover in the enamel organ of the rat incisor. Evidence for ameloblast death immediately after enamel matrix secretion (1977)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 187 (1977), S. 63-97 
    Details
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: During renewal of the enamel organ in the rat incisor cohorts of epithelial cells are transported sequentially through presecretory, secretory and maturation zones to the gingival margin where the life cycles of these cells terminate. This process was examined kinetically by determining the absolute flux of cells within each of these zones of amelogenesis. It was found that the efflux of ameloblasts, stratum intermedium and papillary layer cells from the presecretory zone was about equal to the efflux plus expected growth within the secretory zone. However, between the secretory and maturation zones about 50% more ameloblasts entered the maturation zone than were required to account for the egress at the gingival margin and the expected growth. Since there was no similar imbalance between these zones for papillary layer cells, it was concluded that this discrepancy must represent a 50% reduction in the size of the ameloblast population during the maturation stage of amelogenesis. It was calculated that a little over 25% of the loss occurred immediately at the start of maturation within the region of postsecretory transition and the remaining 25% of the loss occurred throughout the subsequent regions of the maturation zone. In addition to the kinetic analysis graphic reconstructions, or surface maps, of ameloblast nuclei were prepared. These maps illustrated the characteristics of ameloblast nuclear packing within the three zones of amelogenesis and they provided quantitative confirmation that as ameloblasts progress through the maturation zone, there is a loss of cells in an amount predicted by the kinetic analysis.
    Additional Material: 7 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1091870106
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Knife chatter during thin sectioning of rat incisor enamel can cause periodicities resembling cross-striations (1983)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 207 (1983), S. 533-538 
    Details
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Cross-striations are traditionally associated with the enamel rods in many species including man. Although these striations are obvious with light microscopy, their exact nature has been difficult to determine with the transmission electron microscope on thin sections of enamel. Thin section microscopy either reveals no structures that can be called cross-striations, or shows periodic light and dark bands across the rods. Superficially, these bands resemble chatter artifact. To test this possibility, rat incisor enamel was used because cross-striations have not been demonstrated on these enamel rods. Thin sections were prepared of enamel blocks oriented in various ways with respect to the cutting edge of the diamond knife. The sections showed either uniform enamel or light and dark bands over rod profiles or interrod enamel. Since these bands could be produced artifactually it is concluded that similar bands seen on enamel rods of other species may also be artifacts.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1092070315
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    Relationship between the quality of fixation and the presence of stippled material in newly formed enamel of the rat incisor (1984)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 208 (1984), S. 15-31 
    Details
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Extracellular accumulation of a granular material that is presumed to be an organic “precursor” to mineralized enamel has been reported. This material, generally referred to as “stippled material,” was observed mainly after immersion fixation with osmium tetroxide. In studies with perfusion fixation, the presence of stippled material was inconsistent. Therefore, it appeared that the occurrence of stippled material was dependent on the method of fixation. To test this assumption, tissues were fixed by immersion in either osmium tetroxide or glutaraldehyde and by perfusion with either glutaraldehyde or a mixture of acrolein, glutaradehyde, and formaldehyde. It was found that as the quality of cellular preservation improved, the occurrence of stippled material decreased. Since no stippled material could be found in material judged to be well fixed, it was concluded that stippled material is not an extracellular precursor to mineralized enamel, but is a breakdown product resulting from poor fixation.
    Additional Material: 22 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1092080104
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...