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  • 1
    Electronic Resource
    Electronic Resource
    The pig blastocyst: Its ultrastructure and the uptake of protein macromolecules (1984)
    Springer
    Cell & tissue research 235 (1984), S. 347-356 
    Details
    ISSN: 1432-0878
    Keywords: Blastocyst ; Ultrastructure ; Pig
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Between days 8 and 11 of pregnancy spherical blastocysts from 0.3 to 10 mm in diameter were flushed from the uterine horns of Dutch Landrace pigs. A description of their ultrastructure is given, and the uptake of horseradish peroxidase and ferritin is demonstrated. The ultrastructure of the trophoblast was similar at all ages studied. The trophoblast which has many apical microvilli is able to take up and digest the macromolecules which were offered in the in vitro incubation medium. The hypoblast consists of flattened cells. In blastocysts 2 mm and larger, compact cells bearing microvilli are found below the embryoblast. Cell organelles indicating protein synthesis are found within hypoblast cells of such blastocysts. In the embryoblast, local concentrations of cell organelles are visible, indicating that differentiation has started. After the disappearance of Rauber's layer, which takes place when the blastocyst reaches a diameter of about 2 mm, superficial embryoblast cells develop short microvilli. The cells do not absorb ferritin or peroxidase but are dependent on the trophoblast for their food requirements. All cell layers in the blastocyst contain mitochondria that have characteristics of those found in steroidproducing cells. The significance of the uptake and digestion of macromolecules by trophoblast cells, the synthesis of protein by hypoblast cells and the possible synthesis of steroids is discussed with respect to the relationship between the cell layers of the blastocyst and in the context of conceptomaternal relationships.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00217859
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  • 2
    Electronic Resource
    Electronic Resource
    The ultrastructure and renewal of the intestinal epithelium of the juvenile grasscarp, Ctenopharyngodon idella (Val.) (1978)
    Springer
    Cell & tissue research 187 (1978), S. 181-200 
    Details
    ISSN: 1432-0878
    Keywords: Intestine ; Teleost ; Epithelium ; Renewal ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The intestinal absorptive epithelium of starved and fed fish has been studied electron microscopically. After feeding, cells of the proximal segment of the intestine show morphological characteristics of lipid absorption. Absorptive cells in the middle segment contain many pinocytotic vesicles in both fasted and fed specimens. Absorption of protein macromolecules is supposed to be one of the main functions of this part of the gut. In the most caudal part of the intestine, absorptive cells carry relatively few and short microvilli. The proximal and distal segments show structural indications of a function in osmoregulation. The renewal of the epithelium has been studied with light microscopic autoradiography, using tritiated thymidine. The intestinal mucosal fold epithelium represents a cell renewal system. The cells proliferate at the base of the fold and migrate towards the apex in 10–15 days at 20° C. The functional absorptive cells proved to be generally present in the intestinal epithelium, including the proliferative area. Undifferentiated cells have not been identified. The results will be compared with data on absorption of lipid and protein macromolecules in teleostean and mammalian intestines and with descriptions of the cell renewal system in the mammalian intestine.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00224364
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  • 3
    Electronic Resource
    Electronic Resource
    The effects of osmotic experiments and prolactin on the mucous cells in the skin and the ionocytes in the gills of the teleost Cichlasoma biocellatum (1971)
    Springer
    Cell & tissue research 121 (1971), S. 93-101 
    Details
    ISSN: 1432-0878
    Keywords: Prolactin ; Mucous cells ; Ionocytes ; Cichlasoma
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Adult Cichlasoma biocellatum were kept in deionized water, 25% sea-water and tap-water. The mucous cells in the epithelium of the gills and the buccal floor were not affected by the osmotic experiments. In animals kept in deionized water the mucous cells in the skin remained unaffected, but the ionocytes (chloride cells) in the gills were strongly stimulated. Keeping the animals in salt water led to a strong regression of the epidermis including the mucous cells, and of the ionocytes. The regression could be counteracted by prolactin injections. The changes in the skin and the ionocytes could be correlated with the activity of the prolactin producing cells in the adenohypophysis. It is suggested that the epidermis and its mucous cells as well as the ionocytes are under prolactin control.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00330920
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  • 4
    Electronic Resource
    Electronic Resource
    The identification of the thyrotropic cells in the adenohypophysis of the cichlid fish Cichlasoma biocellatum and the role of these cells and of the thyroid in osmoregulation (1971)
    Springer
    Cell & tissue research 121 (1971), S. 82-92 
    Details
    ISSN: 1432-0878
    Keywords: Thyrotrops ; Teleost ; Thyroid ; Prolactin ; Osmoregulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In order to identify the thyrotropic cells in the pituitary gland of Cichlasoma biocellatum, adult animals were treated with thyroxine. Periodic acid Schiff (PAS)- and aldehyde fuchsin (AF)-positive, and Alcian blue (AB)-negative basophils in the meso-adenohypophysis as well as the thyroid were strongly inactivated by such treatment. Since other cell types in the adenohypophysis were not affected, it is concluded that the PAS-positive and AB-negative basophils in the meso-adenohypophysis are the thyrotrops. In normal animals the thyrotrops and the thyroid are very active. Propylthiouracil did not cause a further activation of TSH cells. Keeping the animals in 25% sea-water caused a strong inactivation of the prolactin cells, the thyrotrops and the thyroid. In deionized water the prolactin cells were stimulated, but the thyroid was less active than in controls. Injections of ovine prolactin did not enhance the activity of the thyroid in salt water animals. It is suggested that in Cichlasoma biocellatum prolactin does not have a direct stimulatory effect on the thyroid.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00330919
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  • 5
    Electronic Resource
    Electronic Resource
    Proliferation and differentiation of intestinal epithelial cells during development of Barbus conchonius (Teleostei, Cyprinidae) (1984)
    Springer
    Cell & tissue research 236 (1984), S. 207-216 
    Details
    ISSN: 1432-0878
    Keywords: Development ; Enterocytes ; Fish ; Mitosis ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The processes of proliferation, cell division and differentiation of intestinal epithelial cells have been studied during development of the fish, Barbus conchonius. On the 3rd day, nearly all cells of the presumptive gut proliferate. Once the intestinal epithelium begins to differentiate, a decreasing percentage of proliferative cells can be found. On the 7th day, when intestinal folds start to develop, the proliferative cells become restricted to the future basal parts of the folds. Ultrastructural examination of 3H-thymidine-labeled cells and mitotic cells of 6-day-old larvae shows that functional enterocytes are proliferative. The same feature is suggested for older fish. Proliferating undifferentiated “dark” cells, characterized by many free ribosomes and a few organelles, are also present in the intestinal epithelium of larval fish; they are considered to be stem cells, mainly for goblet cells. Proliferating goblet cells and enteroendocrine cells were not observed. The latter cell type is scarce and has a long turnover time. A common feature of all these dividing cells is the presence of isolated spherical to cylindrical lamellar structures which may have lost contact with the cell membrane during prophase; they probably regain this contact by fusion with the cell membrane at the end of mitosis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00216533
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  • 6
    Electronic Resource
    Electronic Resource
    The ultrastructure of the uterine epithelium of the pig during the estrous cycle and early pregnancy (1986)
    Springer
    Cell & tissue research 246 (1986), S. 81-89 
    Details
    ISSN: 1432-0878
    Keywords: Uterus ; Epithelium ; Ultrastructure ; Pig
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ultrastructure of the endometrial epithelium of the pig was studied during the estrous cycle and early pregnancy up to implantation. Special attention was given to the luminal epithelium and morphological indications of protein synthesis. Although the general morphology of the luminal and glandular epithelia is similar (both tissues consist of secretory cells and ciliated cells at all the stages studied), it appears that the two epithelia should be considered as two functionally different units in the pre-implantation period. Morphological evidence suggests the presence of at least three different secretory products within luminal epithelial cells; they are released at different times, i.e. at estrus, between day 8 and 10 and after day 11. The glandular epithelium shows release of secretory products from day 10–11. Increasing amounts of glycogen were found within epithelial cells, especially in pregnant gilts from day 12. The possible significance of secretory activity of the epithelium is discussed in relation to the development of the embryos.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00219003
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