Epithelial basement membrane of mouse jejunum. Evidence for laminin turnover along the entire crypt-villus axis.
Little is known regarding turnover of the epithelial basement membrane in adult small intestine. Are components degraded and inserted along the length of the crypt-villus axis or selectively in the crypt region with subsequent migration of basement membrane from crypt to villus tip in concert with epithelium? We injected affinity-purified sheep anti-laminin IgG or sheep anti-laminin IgG complexed to horseradish peroxidase (HRP) into mice to label basement membrane laminin in vivo. Fluorescence microscopy revealed linear fluorescence along the length of the jejunal epithelial basement membrane 1 d after anti-laminin IgG injection. By 1 wk, small nonfluorescent domains were interposed between larger fluorescent domains. Over the next 5 wk the lengths of nonfluorescent domains increased progressively whereas those of fluorescent domains decreased. Additionally, electron microscopy revealed HRP reaction product along the length of the epithelial basement membrane after 1 d whereas unlabeled or lightly labeled domains that increased in length with time were observed interposed between heavily labeled domains by 2 and 4 wk along the entire crypt-villus axis. We conclude that laminin turnover occurs focally in the epithelial basement membrane of mouse jejunum along the crypt-villus axis over a period of weeks and that this basement membrane does not comigrate in concert with its overlying epithelium.
Department of Medicine, Brigham and Women's Hospital, Boston, Massachusetts 02115.
J S
JS
Trier
C H
CH
Allan
D R
DR
Abrahamson
S J
SJ
Hagen
D000818:Animals; D001485:Basement Membrane / Q000378:metabolism*; D004848:Epithelium / Q000378:metabolism; D005455:Fluorescent Antibody Technique; D007413:Intestinal Mucosa / Q000378:metabolism*; D007583:Jejunum / Q000378:metabolism*; D007797:Laminin / Q000378:metabolism*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008854:Microscopy, Electron; D013997:Time Factors
D007797:Laminin