Library

feed icon rss

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
    Springer
    Anatomy and embryology 158 (1979), S. 41-50 
    ISSN: 1432-0568
    Keywords: Placenta (human) ; Syncytiotrophoblast ; Intercellular junctions ; Electron microscopy ; Freeze-fracturing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Inter-and intrasyncytiotrophoblastic junctions within the human full term placenta were electronmicroscopically investigated using thin sections and freeze-fracturing. Narrow clefts were occasionally situated between surface areas where adjacent chorionic villi exhibited close contact. Whithin these clefts, extensive zonulae and maculae occludentes and numerous maculae adherentes were found. The zonulae occludentes showed a continuous and irregular course on the membrane surface, and the maculae occludentes were irregularly distributed over extended membrane areas. Besides these areas, maculae occludentes and maculae adherentes were observed on infoldings and invaginations of the syncytiotrophoblastic surface membrane. Investigations of the inner surface of the syncytiotrophoblastic layer, that is, the layer facing the villous stroma, also revealed invaginations joined by maculae adherentes. The functional significance of the inter-and intrasyncytiotrophoblastic junctions is discussed with respect to the differentiation of the trophoblast.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Anatomy and embryology 149 (1976), S. 123-148 
    ISSN: 1432-0568
    Keywords: Rat-placenta ; Gap junctions ; Electron microscopy ; Freeze-fracturing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The placental labyrinth of the chorioallantoic placenta of the rat was studied with transmission and scanning electron microscopy. Full-term placentas were investigated after perfusion fixation from the maternal and fetal circulation, including thin-sectioning and freeze-fracturing. The labyrinthal three-dimensional structure was found not to be trabecular but spongious lamellar. We propose a division of the lamellae into three groups—the first, second, and third order. The trophoblastic layers are described in detail, showing a cellular layer I and two syncytial layers II and III. Layer I is found to be fenestrated and highly permeable. Layers II and III are connected by extended gap junction areas. It is suggested that the gap junctions function as a molecular sieve and represent the limiting barrier in diaplacental transport of the choriollantoic placenta. Fetal capillaries are fenestrated and endothelial cells are connected by tight junctions. The functional significance of the morphologic findings is discussed.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 3
    ISSN: 1432-1246
    Keywords: Diesel exhaust emission ; Liver ; Electron microscopy ; Freeze-fracture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The livers of Syrian golden hamsters were examined with the light and electron microscope using the techniques of thin sectioning and freeze-fracture following 5 months of exposure to various concentrations of diluted diesel exhaust gases. The light microscopical examination showed enlarged sinusoides with activated Kupffer's cells and slight changes in the cell nuclei. In the electron microscopical examination the most striking changes were seen in the mitochondria, which frequently showed a loss in cristae. In addition, the mitochondria exhibited pleomorphic character. The microbodies were of the same size as mitochondria. An increase in the number of lysosomes was observed especially in the tissue surrounding the narrow bile canaliculi. The various alterations corresponding to the different concentrations of exhaust gases could be seen especially well in the sinusoides, the mitochondria and the microbodies. In general the hepatocytes appeared to be moderately enlarged. The zonulae occludentes showed a more irregular outline and large maculae tight junctions were found on the lateral region of the plasmalemma of hepatocytes. The gap junctions exhibited a wide range of structural diversity. The intramembranous particles on the P fracture face of the plasmalemma of hepatocytes are aggregated.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 4
    Electronic Resource
    Electronic Resource
    Springer
    International archives of occupational and environmental health 49 (1982), S. 305-314 
    ISSN: 1432-1246
    Keywords: Polycyclic aromatic hydrocarbon ; Liver ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Female NMRI mice aged 9–12 weeks were each given a single subcutaneous injection of 0.5 ml of a suspension containing either the total extracts or the polycyclic aromatic hydrocarbon (PAH) fraction of airborne particles. Both the total extracts and PAH fractions contain 3 Vg benzopyrene. After about 15 months the livers were removed from the animals, which had by that time developed tumors at the injection site, and were subjected to ectronmicroscopical study. The essential alterations were observed in the nucleoli and the cell nuclei, which had greatly proliferated and exhibited irregular nuclear membranes. Advanced fibrosis was observed in central liver specimens of all groups. Marked alterations were also observed in the mitochondria and the mitochondria) cristae as well as in the bile canaliculi. Intracytoplasmic glycogen usually occurred densely clustered along the periphery of the cell. It may be concluded from the observations that both the total extract of atmospheric suspended particulate matter and the PAH fraction cause hematogenic damage to the liver following subcutaneous injection, a finding which cannot be interpreted as metastatic carcinoma.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 172 (1976), S. 157-169 
    ISSN: 1432-0878
    Keywords: Placenta (Human) ; Capillaries ; Tight junctions ; Electron microscopy ; Freeze-fracturing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ultrastructure of human placental capillaries was investigated using perfusion fixation and the freeze-fracturing technique. The capillaries have a continuous endothelium especially rich in microfilaments, whereas micropinocytotic vesicles are exceedingly scarce. The endothelial cells are connected by three types of junctions: (1) zonulae occludentes characterized by 2 to 4 focal regions of membrane contact in thin-sectioned specimens and an equal number of ridges on the membrane E-face in freeze-fractured specimens; (2) small gap junctions associated with the zonula occludens. (3) attachment plaques resembling zonulae adhaerentes in their fine structure. Endothelial cells are provided with long, circularly oriented pseudopodial extensions, which may be responsible for intermittent constrictions of the vessel lumen. These findings indicate that diaplacental transport at the level of the fetal capillary is controlled by the cytoplasm of the endothelial cells and probably occurs only to a very limited extent by way of micropinocytotic vesicles.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 6
    Electronic Resource
    Electronic Resource
    Springer
    European archives of oto-rhino-laryngology and head & neck 254 (1997), S. 396-400 
    ISSN: 1434-4726
    Keywords: Guinea pig hair cells ; Electron microscopy ; Immunocytochemistry ; Nitric oxide synthase ; Sound transduction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Nitric oxide synthase (NOS) activity has been detected previously in the mammalian cochlea at a light microscopic level. Here we present results of electron microscopic analysis for post-embedding immunoreactivity of neural-type NOS I in the cochlea of the guinea pig. Strong enzyme immunoreactivity was identified in the cytoplasm of inner and outer hair cells. Gold-labeled NOS I antibodies were mainly located in electron-dense areas of the cytoplasm, whereas electron-lucent regions of the receptor cells were nearly free from any immunoreactivity. In both types of hair cells anti-NOS I antibodies were also visible in the cuticular plates, hair bundles and nuclei. Further ultrastructural analysis revealed that the submembranous cisternae of the outer hair cells were nearly free from any reaction product, demonstrating that the whole cytoplasm of this hair cell was not immunoreactive. Other NOS I immunoreactivity was identified in the cuticular plates of the inner and outer pillar cells and in the cytoskeletal elements located in the apical parts of Deiter cells, forming the lamina reticularis or in cytoskeletal-containing regions in basal Deiter cells. Anti-NOS antibodies were visible in the nuclei of various cell types. Our findings suggest that nitric oxide produced by NO I synthase in the organ of Corti may act as a modulator of hair cell physiology during the processes of signal transduction with frequence selectivity.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 7
    Electronic Resource
    Electronic Resource
    Springer
    European archives of oto-rhino-laryngology and head & neck 245 (1988), S. 279-283 
    ISSN: 1434-4726
    Keywords: Calcium ; Reissner's membrane ; Stria vascularis ; Limbus ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Cations were precipitated with potassium antimonate in the cochlea of the guinea pig and electron microscopy was used to analyze the distribution of the formed reaction products. Differences in precipitate density between neighboring cells in Reissner's membrane, in the stria vascularis and in the limbus are described. Electron spectroscopic imaging was performed to obtain information about the spatial distribution of the precipitates and their elemental composition.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 8
    ISSN: 0570-0833
    Keywords: Scanning probe microscopy ; Nobel lecture ; Electron microscopy ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...