Distribution of fibronectin-containing structures on the surface of lamelloplasm and endoplasm of fibroblasts; hypothesis of receptor-mediated assembly of fibronectin structures

Distribution of fibronectin-containing structures on the surface of different cell parts of substrate-spread normal mouse fibroblasts was examined by indirect immunofluorescence. Relatively large fibronectin fibrils were preferentially located on the surface of central cell part (endoplasm) while peripheral cell part (lamelloplasm) was characterized by the presence of smaller structures (“spots” and “streaks”). Colcemid-treated fibroblasts had similar distribution of fibronectin; cytochalasin B-treated cells had mostly fibronectin spots on all parts of the surface. It is suggested that centripetal movement of receptor-attached fibronectin molecules on the cell surface may promote the formation of fibronectin fibrils.