Confocal microscopy immunofluorescence localization of desmin and other intermediate filament proteins in fetal rat livers

Authors

  • Ph.D. Jany Vassy,

    Corresponding author
    1. Laboratoire de Microscopie Quantitative en Histopathologie, Unité de Recherches Biomathématiques et Biostatistiques, INSERM U 263, Université Paris VII, 75251 Paris Cedex 05
    • Laboratoire de Microscopie Quantitative en Histopathologie, INSERM U 263, Université Paris VII, Tour 53–1, 2 Place Jussieu, 75251 Paris Cedex 05, France
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  • Jean Paul Rigaut,

    1. Laboratoire de Microscopie Quantitative en Histopathologie, Unité de Recherches Biomathématiques et Biostatistiques, INSERM U 263, Université Paris VII, 75251 Paris Cedex 05
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  • Dominique Briane,

    1. Laboratoire de Biologie du Développement et de la Différenciation, Unité de Formation et de Recherche Biomédicale de Bobigny, Université Paris XIII, 93012 Bobigny Cedex, France
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  • Michel Kraemer

    1. Laboratoire de Biologie du Développement et de la Différenciation, Unité de Formation et de Recherche Biomédicale de Bobigny, Université Paris XIII, 93012 Bobigny Cedex, France
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Abstract

Immunolocalization of desmin in fetal rat livers shows that on day 12 of gestation a high number of liver cells express desmin. This number decreases from day 14 onward. On day 20 about the same density of desmin-containing cells is found in fetal rat livers as is found in adult rat livers. Desmin-containing cells show two types of labeling patterns, especially on days 12 and 13 of gestation: (a) a basketlike network of intermediate filaments throughout the whole cell, similar to the labeling pattern of cytokeratin in hepatocytes; and (b) more strongly labeled intermediate filaments developing long and slender processes between adjacent cells, close to the labeling pattern of Ito cells in adult rats. From day 14 of gestation, the first type becomes rare, and from day 18 only the second type remains. Double-labeling experiments show that coexpression of desmin and cytokeratin is found in cells of the first type on days 12, 13 and 14 of gestation. Cells containing desmin with the labeling pattern of the second type never express cytokeratin. Coexpression of vimentin and cytokeratin is never found in fetal hepatocytes, even on day 12 of gestation. Numerous nonhepatocyte cells coexpress desmin and vimentin, but some cells contain vimentin or desmin alone. In desmincontaining cells the labeling pattern is of the first type (basketlike network). These results suggest that in early stages of fetal liver development, desmin is found in two different types of liver cells. Cells of the first type contain cytokeratin and desmin, and those of the second type contain desmin and vimentin, as Ito cells in adult liver tissue. Cells of the first type might represent a particular type of fetal hepatocyte. The existence of these two types of desmin immunolocalization is in convergence with electron microscopic data showing numerous lipid droplets both in fetal hepatocytes and in perisinusoidal cells. It is generally admitted that fetal liver differentiation is the result of the close association between endodermal and mesenchymal cells. Among the latter, desmin-containing cells (fetal Ito cells) might play a crucial role, especially because they are known to contain vitamin A and to express a hepatocyte growth factor in the normal adult liver. (HEPATOLOGY 1993;17:293–300.)

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