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  • 1
    Electronic Resource
    Electronic Resource
    Connective tissue is involved in adult epithelial development of the small intestine during anuran metamorphosis in vitro (1992)
    Springer
    Development genes and evolution 201 (1992), S. 322-329 
    Details
    ISSN: 1432-041X
    Keywords: Intestinal epithelium ; Anuran metamorphosis ; Organ culture ; Tissue interaction ; Regional difference
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The role of connective tissue in metamorphic changes of the small intestinal epithelium inXenopus laevis tadpoles was investigated by using organ culture techniques and electron microscopy. Tissue fragments isolated from various parts of the small intestine at stage 57 were cultivated. Larval cell death of the epithelium was induced by thyroid hormone in all fragments, whereas adult epithelial development was observed only in fragments isolated from the anterior intestinal region containing the typhlosole where most of the larval connective tissue was localized. The epithelium was then cultivated in recombination with homologous or heterologous non-epithelial components. The adult epithelium developed only in recombinants containing a thick connective tissue layer from the typhlosole. There was no regional difference in the developmental potency of the epithelium itself. In all explants where adult epithelium developed, the connective tissue increased in cell density just beneath the epithelium, which was rapidly proliferating and forming typical islets. At the same time, fibroblasts possessing well-developed rough endoplasmic reticulum differentiated close to epithelial cells and often made contact with them. These results indicate that the connective tissue originating from the typhlosole plays an important role in adult epithelial development of the anuran small intestine, probably via direct cell-to-cell contacts or some factor(s) synthesized by the fibroblasts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00592113
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  • 2
    Electronic Resource
    Electronic Resource
    Demonstration of sucrase immunoreactivity of the brush border induced by duodenal mesenchyme in chick stomach endoderm (1992)
    Springer
    Development genes and evolution 201 (1992), S. 389-392 
    Details
    ISSN: 1432-041X
    Keywords: Sucrase-Brush border ; Mesenchymal induction ; Stomach endoderm ; Immunoelectron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary When stomach endoderm of chick embryos was recombined and cultured with duodenal mesenchyme, the endoderm developed a brush border structure over a large area and also differentiated into mucous cells in a small area according to its own developmental fate. In the present investigation, we examined whether the induced brush border structure expressed sucrase antigen by immunoelectron microscopy using the antiserum raised against chicken sucrase. Sucrase immunoreactivity could be detected as ferritin particles in the region where the brush border was induced, whereas it was never detected on microvilli of endodermal cells which differentiated into the mucous cells. Thus, almost all of the endodermal cells could be identified as either small intestine-type cells possessing the sucrase antigen or stomach-type cells possessing mucous granules but not the sucrase antigen. The results indicate that stomach endodermal cells of chick embryos can differentiate not only morphologically but also functionally into typical intestinal epithelial cells under the inductive influence of the duodenal mesenchyme.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00365127
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  • 3
    Electronic Resource
    Electronic Resource
    Cell-specific and spatio-temporal expression of intestinal fatty acid-binding protein gene during amphibian metamorphosis (1994)
    Springer
    Development genes and evolution 204 (1994), S. 150-155 
    Details
    ISSN: 1432-041X
    Keywords: Fatty-acid-binding protein ; Intestinal epithelium ; In situ hybridization ; Anuran metamorphosis ; Regional difference
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Intestinal fatty acid-binding protein (IFABP) gene is known to be regulated during Xenopus metamorphosis. To determine the relationship between its regulation and cellular differentiation during metamorphosis, we have examined the distribution of IFABP mRNA in the Xenopus digestive tract by in situ hybridization techniques. Throughout all stages examined, transcripts of IFABP gene were observed exclusively in absorptive epithelial cells of the small intestine, and they decreased in amount towards the posterior intestine. Around stage 58, just before metamorphic climax, IFABP mRNA level began to decrease in larval absorptive cells that still remained intact morphologically. Thereafter, IFABP mRNA was no longer detected among larval cells. In turn, at stage 62, IFABP mRNA became detectable in some of the newly formed adult epithelium that had not yet developed a brush border, but not in the remaining larval cells. By the end of metamorphosis, IFABP mRNA became more abundant towards the crest of intestinal folds. These results suggest that IFABP gene expression is specific for absorptive epithelial cells of the small intestine and is regionally regulated along the intestinal anterior-posterior axis in both tadpoles and frogs and also along the trough-crest axis of frog intestinal folds. In addition, our present study directly shows that IFABP mRNA level decreases in larval absorptive cells but increases in adult ones during metamorphosis, preceding morphological changes of both types of cells. Therefore, the regulation of IFABP gene is an early event during both larval epithelial cell death and adult epithelial cell differentiation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00361110
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  • 4
    Electronic Resource
    Electronic Resource
    Inductive action of epithelium on differentiation of intestinal connective tissue of Xenopus laevis tadpoles during metamorphosis in vitro (1994)
    Springer
    Cell & tissue research 277 (1994), S. 427-436 
    Details
    ISSN: 1432-0878
    Keywords: Key words: Anuran metamorphosis ; Small intestine ; Macrophage ; Fibroblast ; Tissue interaction ; Differentiation ; Organ culture ; Xenopus laevis (Anura)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. The action of the epithelium on differentiation of connective tissue cells of Xenopus small intestine during metamorphosis was investigated by using culture and morphological techniques. Connective tissue fragments isolated from the small intestine at stage 57 were cultivated in the presence or absence of homologous epithelium. In the presence of the epithelium, metamorphic changes in the connective tissue were fully induced by hormones including thyroid hormone (T3), as during spontaneous metamorphosis, whereas they were partially induced in the absence of the epithelium. Macrophage-like cells showing non-specific esterase activity in the connective tissue were much fewer in the absence of the epithelium than in the presence of it, and aggregates of fibroblasts possessing well-developed rough endoplasmic reticulum developed only in the presence of the epithelium. Just before the aggregation of the fibroblasts, the connective tissue close to the epithelium became intensely stained with concanavalin A (ConA) and wheat germ agglutinin (WGA). The present results indicate that the epithelium plays important roles in the differentiation of intestinal connective tissue cells, which in turn affect the epithelial transformation from larval to adult form during anuran metamorphosis. Thus, the tissue interaction between the epithelium and the connective tissue in the anuran small intestine is truly bidirectional.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00300215
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  • 5
    Electronic Resource
    Electronic Resource
    Inductive action of epithelium on differentiation of intestinal connective tissue of Xenopus laevis tadpoles during metamorphosis in vitro (1994)
    Springer
    Cell & tissue research 277 (1994), S. 427-436 
    Details
    ISSN: 1432-0878
    Keywords: Anuran metamorphosis ; Small intestine ; Macrophage ; Fibroblast ; Tissue interaction ; Differentiation ; Organ culture ; Xenopus laevis (Anura)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The action of the epithelium on differentiation of connective tissue cells of Xenopus small intestine during metamorphosis was investigated by using culture and morphological techniques. Connective tissue fragments isolated from the small intestine at stage 57 were cultivated in the presence or absence of homologous epithelium. In the presence of the epithelium, metamorphic changes in the connective tissue were fully induced by hormones including thyroid hormone (T3), as during spontaneous metamorphosis, whereas they were partially induced in the absence of the epithelium. Macrophage-like cells showing non-specific esterase activity in the connective tissue were much fewer in the absence of the epithelium than in the presence of it, and aggregates of fibroblasts possessing well-developed rough endoplasmic reticulum developed only in the presence of the epithelium. Just before the aggregation of the fibroblasts, the connective tissue close to the epithelium became intensely stained with concanavalin A (ConA) and wheat germ agglutinin (WGA). The present results indicate that the epithelium plays important roles in the differentiation of intestinal connective tissue cells, which in turn affect the epithelial transformation from larval to adult form during anuran metamorphosis. Thus, the tissue interaction between the epithelium and the connective tissue in the anuran small intestine is truly bidirectional.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00300215
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  • 6
    Electronic Resource
    Electronic Resource
    Changes in lectin-binding pattern in the digestive tract of Xenopus laevis during metamorphosis. I. Gastric region (1990)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 205 (1990), S. 1-8 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The distribution of structural and secretory glycoconjugates in the gastric region of metamorphosing Xenopus laevis was studied by the avidin-biotinperoxidase (ABC) histochemical staining method using seven lectins (concanavalin A, Con A; Dolichos biflorus agglutinin, DBA; peanut agglutinin, PNA; Ricinus communis agglutinin I, RCA-I; soybean agglutinin, SBA; Ulex europeus agglutinin I, UEA-I; and wheat germ agglutinin, WGA). Throughout the larval period to stage 60, the epithelium consisting of surface cells and gland cells was stained in various patterns with all lectins examined, whereas the thin layer of connective tissue was positive only for RCA.-I. At the beginning of metamorphic climax, the connective tissue became stained with Con A, SBA, and WGA, and its staining pattern varied with different lectins. The region just beneath the surface cells was strongly stained only with RCA-I. With the progression of development, both the epithelium and the connective tissue gradually changed their staining patterns. The surface cells, the gland cells, and the connective tissue conspicuously changed their staining patterns, respectively, for Con A and WGA; for Con A, PNA, RCA-I, SBA, and WGA; and for Con A, RCA -I, and WGA. At the completion of metamorphosis (stage 66), mucous neck cells became clearly idpntifiable in the epithelium, and their cytoplasm was strongly stained with DBA, PNA, RCA-I, and SBA. These results indicate that lectin histochemistry can provide good criteria for distinguishing among three epithelial cell types, namely, surface cells, gland cells, and mucous neck cells, and between adult and larval cells of each type.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1052050102
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  • 7
    Electronic Resource
    Electronic Resource
    Changes in lectin-binding pattern in the digestive tract of Xenopus laevis during metamorphosis. II. Small intestine (1990)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 205 (1990), S. 9-15 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The binding of seven lectins (concanavalin A, Con A; Dolichos biflorus agglutinin, DBA; peanut agglutinin, PNA; Ricinus communis agglutinin I, RCA-I; soybean agglutinin, SBA; Ulex europeus agglutinin, UEA-I; and wheat germ agglutinin, WGA) to the small intestine in metamorphosing Xenopus laevis was studied by the avidin-biotin-peroxidase (ABC) method. The staining pattern of the epithelium with all lectins except for UEA-I and Con A changed gradually during metamorphic climax; the main component of the epithelium, absorptive cells, gradually became positive for DBA, PNA, and SBA and the scattered goblet cells for RCA-I and WGA. On the other hand, the change of the staining pattern in the connective tissue occurred only for Con A, RCA-I, and WGA, and this change took place rapidly at the beginning of climax (stage 60). Increased staining for Con A and WGA at stage 60 was observed only in a group of connective tissue cells close to the epithelium and in the basement membrane. As metamorphosis progressed, this localization of the staining intensity became less clear. At the completion of metamorphosis (stage 66), the absorptive cells were stained with all lectins except for UEA-I, whereas the goblet cells stained only with RCA-I and WGA. These results indicate that lectin histochemistry can distinguish between larval and adult cells of both two epithelial types (absorptive and goblet cells). The technique may also identify a group of connective tissue cells, close to the epithelium, that possibly induce the metamorphic epithelial changes.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1052050103
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  • 8
    Electronic Resource
    Electronic Resource
    Programmed cell death and heterolysis of larval epithelial cells by macrophage-like cells in the anuran small intestine in vivo and in vitro (1992)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 213 (1992), S. 185-195 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The degenerative processes in the larval small intestine of Xenopus laevis tadpoles during spontaneous metamorphosis and during thyroid hormone-induced metamorphosis in vitro were examined by electron microscopy. Around the beginning of spontaneous metamorphic climax (stages 59-61), both apoptotic bodies derived from larval epithelial cells and intraepithelial macrophage-like cells suddenly increase in number. The macrophage-like cells become rounded and enlarged because of numerous vacuoles containing the apoptotic bodies. Mitotic profiles of the macrophage-like cells, however, are localized in the connective tissue where different developmental stages of macrophage-like cells are present. After stage 62, the intraepithelial macrophage-like cells decrease in number, while large macrophage-like cells which include the apoptotic bodies and retain intact cell membranes and nuclei appear in the lumen. Degenerative changes similar to those during spontaneous metamorphosis described above could be reproduced in vitro. In tissue fragments isolated from the small intestine of stage 57 tadpoles and cultured in the presence of thyroid hormone, the number of intraepithelial macrophage-like cells reaches its maximum around the 3rd day of cultivation when the larval epithelial cells most rapidly decrease in number. These results suggest that the rapid degeneration of larval epithelial cells occurs not only because of apoptosis of the epithelial cells themselves but also from heterolysis by macrophages. The macrophages probably originate in the connective tissue, actively proliferate, migrate into the larval epithelium around the beginning of metamorphic climax, and are finally extruded into the lumen. © 1992 Wiley-Liss, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1052130205
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  • 9
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    Inductive action of epithelium on differentiation of intestinal connective tissue of Xenopus laevis tadpoles during metamorphosis in vitro (1994)
    Springer
    Details
    Publication Date: 1994-08-01
    Print ISSN: 0302-766X
    Electronic ISSN: 1432-0878
    Topics: Biology , Medicine
    Published by Springer
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  • 10
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    Inductive action of epithelium on differentiation of intestinal connective tissue of Xenopus laevis tadpoles during metamorphosis in vitro (1994)
    Springer
    Details
    Publication Date: 1994-09-01
    Print ISSN: 0302-766X
    Electronic ISSN: 1432-0878
    Topics: Biology , Medicine
    Published by Springer
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