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  • 1
    Electronic Resource
    Electronic Resource
    Freeze-fracture images of mammary glands of lactating mice (1981)
    Springer
    Anatomy and embryology 163 (1981), S. 173-183 
    Details
    ISSN: 1432-0568
    Keywords: Freeze-fracture ; Mammary gland ; Apocrine process ; Membrane particles ; Granule fusion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Thin section as well as freeze-fracture images of lactating mouse mammary glands were examined with the electron microscope. The well-developed tight junction, consisting of 5–8 strands, is present at the apical part of the lateral plasma membranes of the adjacent glandular cells. The secretory products in this cell are classified into two types, milk fat globules without cores and proteinous granules having dense cores. Some proteinous granules fuse with each other to become larger structures. Membrane particles of the limiting membranes of both adjacent granules are cleared off from the initial site of the fusion. A large apocrine process including a large fat droplet, a few small proteinous granules, and little cytoplasmic matrix is sometimes seen. In addition, some proteinous granules are released by exocytosis. At exocytosis, the membrane particles are cleared off from the fusion site of the plasma membrane and the granule limiting membrane just before the fusion occurs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00320674
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  • 2
    Electronic Resource
    Electronic Resource
    Freeze-Fracture images on filipin-sterol complexes in the thyroid follicle epithelial cell of mice with special regard to absence of cholesterol at the site of micropinocytosis (1981)
    Springer
    Histochemistry and cell biology 73 (1981), S. 57-63 
    Details
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In order to clarify the distribution of cholesterol in the plasma-and cyto-membranes of the thyroid follicle cell, freeze-fracture images of the filipin-treated tissues of normal and TSH-treated mice were observed. The filipin-sterol complexes, 25 to 30 nm protuberances or pits are distributed densely and almost homogeneously on the fractured plasma membrane, though the small depressions showing aggregates of intramembrane particles lack the complexes. Each depression corresponds to the coated pit, which might be an initial site for micropinocytosis of the luminal colloid. The limiting membranes of all the large colloid droplets reabsorbed are generally very rich in the complexes, but some small regions on the limiting membrane of the droplet are less in their density. The membranes of the rough endoplasmic reticulum, of the nucleus and of the Golgi apparatus are almost free from the complexes, though small clusters consisting of 2–5 complexes are rarely scattered. In thin sections, the membranes which are rich in the filipinsterol complexes become obscure in their fine structure after treatment with filipin for 12–14 h.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00493133
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Fine structural studies on the reabsorption of colloid and fusion of colloid droplets in thyroid glands of TSH-treated mice (1982)
    Springer
    Cell & tissue research 223 (1982), S. 519-532 
    Details
    ISSN: 1432-0878
    Keywords: Thyroid ; Colloid reabsorption ; Actin filament ; Micropinocytosis ; Freeze-fracture ; Freeze substitution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The mechanism of the luminal colloid reabsorption and the fate of reabsorbed colloid droplets were studied ultracytochemically in epithelial cells of thyroid cells of TSH-treated mice. The luminal colloid is reabsorbed by micropinocytosis as well as phagocytosis into the follicle epithelial cell. Almost all the pinocytotic pits and vesicles are coated and often closely associated with actin filaments demonstrated by use of heavy meromyosin (HMM). This suggests the involvement of the actin filament system in making and transporting coated vesicles for micropinocytosis of the luminal colloid. Freeze-fracture images show aggregates of intramembrane particles on the P-face of the small depressions corresponding to the initial site for coated pits. The reabsorbed colloid droplets fuse with one another and with lysosomes. At the initial stage of this fusion, the limiting membranes of adjoining droplets fuse in a limited area to become pentalaminar, and then become trilaminar. Eventually, the membranes at the fusion point disappear, and the contents of both droplets become continuous. Freeze-fracture images reveal the disappearance of the intramembrane particles at the initial site where the fusion occurs. Examination of thin-sectioned tissue treated by rapid-freeze substitution fixation, shows clearly delineated cell organelles, and the rounded mitochondria have a characteristically high electron-dense matrix. Just beneath the limiting membrane of each colloid droplet, there always exists a low electron-dense layer about 10 nm thickness. The lysosomes are sometimes seen wrapped around the colloid droplet.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00218473
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Immunocytochemical demonstration of caldesmon and actin in thyroid glands of rats (1984)
    Springer
    Cell & tissue research 237 (1984), S. 375-377 
    Details
    ISSN: 1432-0878
    Keywords: Thyroid ; Immunocytochemistry ; Caldesmon ; Actin ; Endocytosis ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The distribution of caldesmon (a calmodulin-binding, F-actin interacting protein; Sobue et al. 1982) and actin was studied in the rat thyroid gland by means of light-microscopic immunocytochemistry, and the fine-structural distribution of actin filaments was examined by use of heavy meromyosin (HMM). Caldesmon and actin were demonstrated in the apical cytoplasm of almost all the follicle epithelial cells in normal as well as TSH-treated animals. Immunoreactivities for both caldesmon and actin showed almost the same pattern in localization. The smooth muscle cells of the blood vessels were also positive for caldesmon and actin. By electron microscopy, numerous actin filaments decorated by HMM and running perpendicularly or randomly to the apical surface were recognized in the apical cytoplasm of the follicle epithelial cell. These results suggest that caldesmon and actin, in conjugation with calmodulin, play a role in the regulation of cellular activity such as exocytosis and endocytosis in the apical portion of the follicle epithelial cell.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00217161
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    Effects of tunicamycin on thin-section and freeze-fracture images of microvilli of the duodenal epithelial cells of the mouse (1984)
    Springer
    Cell & tissue research 238 (1984), S. 653-656 
    Details
    ISSN: 1432-0878
    Keywords: Tunicamycin ; Glycoprotein ; Intestinal epithelium ; Microvilli ; Freeze-fracture ; Mouse
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The effect of tunicamycin, which is known to inhibit the synthesis of N-linked glycoprotein, on the duodenal absorptive epithelial cell of the mouse was studied in thin-section as well as freeze-fracture images. In tunicamycin-treated animals, the apical part of the epithelial cell was almost negative to the PAS reaction. Moreover, microvilli of the epithelial cell became shorter, larger in diameter, and fewer in number in tunicamycin-treated mice. In addition, freeze-fracture images revealed that the population density of membrane particles of the microvillus membrane was lowered by tunicamycin treatment. These results may indicate that the inhibition of synthesis of N-linked glycoprotein causes a decrease of membrane supply from the Golgi apparatus to the apical plasma membrane.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00219885
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  • 6
    Electronic Resource
    Electronic Resource
    Immunocytochemical demonstration of caldesmon (a calmodulin-binding, F-actin-interacting protein) in smooth muscle fibers and absorptive epithelial cells in the small intestine of the rat (1984)
    Springer
    Cell & tissue research 235 (1984), S. 207-209 
    Details
    ISSN: 1432-0878
    Keywords: Caldesmon ; Actin ; Immunocytochemistry ; Small intestine ; Smooth muscle ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The distribution of caldesmon (a calmodulin-binding, F-actin-interacting protein) (Sobue et al. 1982) and of actin was studied in the rat's small intestine by means of light-microscopic immunocytochemistry. Positive immunostaining for caldesmon was seen in smooth muscle cells of the intestinal wall, and of blood vessels, and in the apical portion of the absorptive epithelial cells. The immunoreactivity in goblet cells was difficult to recognize. The positive reaction to immunostaining for actin showed almost the same pattern as that for caldesmon. These results suggest that this calmodulin-binding protein may play an important role in the control of actin-myosin interaction in smooth muscle cells and in non-muscle cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00213742
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