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Ultrastructure of developing kidney glomerular basement membranes: Temporal changes in binding of anti‐laminin lgG and cationized ferritin
Author(s) -
Abrahamson Dale R.,
John Patricia L. St.
Publication year - 1994
Publication title -
microscopy research and technique
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.536
H-Index - 118
eISSN - 1097-0029
pISSN - 1059-910X
DOI - 10.1002/jemt.1070280202
Subject(s) - laminin , basement membrane , glomerular basement membrane , polyclonal antibodies , ferritin , epitope , chemistry , gene isoform , microbiology and biotechnology , podocyte , immunogold labelling , glomerulus , biology , pathology , biochemistry , ultrastructure , extracellular matrix , kidney , antibody , anatomy , immunology , glomerulonephritis , medicine , endocrinology , proteinuria , gene
In vivo labeling of infant rat and mouse glomerular basement membranes (GBMs) with polyclonal anti‐laminin IgGs results in binding across the full widths of GBMs at all stages of development. These stages include the pre‐fusion, double basement membranes found beneath endothelial cells and podocytes in early glomeruli, and the subepithelial matrix outpockets where newly synthesized GBM is spliced into fused basement membrane during glomerular maturation. Identical binding results are obtained either with peroxidase or post‐embedding immunogold techniques. Although injected cationized ferritin also binds abundantly to all developing GBMs, it quickly disappears and, 24 hours after injection, is generally absent from GBMs but remains within mesangial matrices. Injection of newborn mice with monoclonal anti‐laminin IgGs results in dense labeling of pre‐fusion GBMs but post‐fusion GBMs and subepithelial outpockets are weak‐negative. Although masking can not be excluded, these results indicate that laminin epitopes are removed during GBM fusion and splicing, either by isoform substitution or proteolytic processing. The loss of bound cationized ferritin is believed to occur mainly through rapid turnover of GBM proteoglycans. © 1994 Wiley‐Liss, Inc.