In Vivo Assembly of Tight Junctions in Fetal Rat Liver

Examination of glutaraldehyde-fixed, freeze-fractured livers from 14-15-day rat fetuses provided the basis for the following observations. Membrane particles align in otherwise poorly particulated areas of the presumptive pericanalicular plasma membrane (A face), frequently forming a discontinuous &...

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Bibliographic Details
Published in:The Journal of cell biology 1975-11, Vol.67 (2), p.310-319
Main Authors: Montesano, Roberto, Friend, Daniel S., Perrelet, Alain, Orci, Lelio
Format: Article
Language:English
Subjects:
Animals
Beta cells
Bile
Cell Membrane - ultrastructure
Cell membranes
Cells
Endoplasmic Reticulum - ultrastructure
Freeze Fracturing
Gap junctions
Gestational Age
Hepatocytes
Intercellular Junctions - ultrastructure
Liver
Liver - embryology
Liver - ultrastructure
Particulate matter
Rats
Solar fibrils
Tight junctions
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Summary:Examination of glutaraldehyde-fixed, freeze-fractured livers from 14-15-day rat fetuses provided the basis for the following observations. Membrane particles align in otherwise poorly particulated areas of the presumptive pericanalicular plasma membrane (A face), frequently forming a discontinuous "honey-comb" network joining small particle islands. Even at this early stage, contiguous B-fracture faces contain furrows, rather than rows of pits, distinguishing the linear particle aggregates on the A face as developing tight junctions rather than gap junctions. Short segments of these linear arrays merge with smooth ridges clearly identifiable as segments of discontinuous tight junctions. With the continuing confluence of particulate and smooth ridge segments, mature tight junctions become fully appreciable. We conclude that tight junctions form de novo by the alignment and fusion of separate particles into beaded ridges which, in turn, become confluent and are transformed into continuous smooth ones. At 21 days of fetal life, most of the images of assembly have disappeared, and the liver reveals well-formed bile canaliculi sealed by mature tight junctions.
ISSN:0021-9525
1540-8140
DOI:10.1083/jcb.67.2.310