title: Masking of extracellular collagen and the co-distribution of collagen and fibronectin during matrix formation by cultured embryonic fibroblasts.
abstract: Embryonic chicken heart fibroblasts (CHF) were examined by double immunofluorescence in order to study the interactions of collagen and fibronectin. Double-labelling studies of permeabilized whole mounts of CHF, cultured for 15 min to 2 days after plating, detected extracellular collagen at very early times (15 min to 1 h) but not at times later than 3 h. Abundant fibronectin was seen at all times. These observations suggested that the collagen/procollagen antigen was being "masked' by matrix components at the later times. This possibility was tested in two ways: (1) immunolabelling of frozen sections of multilayered 4-day CHF cultures, which showed extensive extracellular collagen superimposable with fibronectin. (2) Limited trypsinization of 4-day CHF cultures, which allowed collagen to be immunolabelled concomitantly with a partial decrease in the degree of fibronectin labelling. The results are discussed in terms of the secretion and assembly of collagen and fibronectin in cultures of embryonic fibroblasts.
mesh_terms: D000818:Animals; D000906:Antibodies; D002478:Cells, Cultured; D002642:Chick Embryo; D003094:Collagen / Q000096:biosynthesis* / Q000276:immunology; D005347:Fibroblasts / Q000378:metabolism; D005353:Fibronectins / Q000096:biosynthesis* / Q000276:immunology; D005455:Fluorescent Antibody Technique; D006321:Heart / Q000196:embryology; D009206:Myocardium / Q000378:metabolism; D013997:Time Factors; D014357:Trypsin
chemical_list: D000906:Antibodies; D005353:Fibronectins; D003094:Collagen; D014357:Trypsin