Abstract
Cell surface fibronectin, an adhesive glycoprotein which is important in maintaining the normal phenotype of cells, was checked with cytofluorometry using an indirect immunofluorescent technique. This method enabled us to measure the amount of fibronectin not only in single whole cells, but in uniformly distributed cells as a whole. The fibronectin content in a sparse culture of human fibroblasts increased linearly until the 4th day after inoculation. In more prolonged cell cultures, fibronection increased at a higher rate than that in the earier culture period. In a confluent culture re-fed with fresh medium containing 10% fetal calf serum, the amount of fibronectin increased and appeared as a matrix substance in the extracellular space. In contrast, in a confluent cell culture re-fed with serum-free medium, the amount of fibronectin decreased for several days.
