Fibronectin in evolution: presence in invertebrates and isolation from Microciona prolifera.

Fibronectin is found in the tissues of a series of vertebrates and invertebrates which suggests its appearance with the simplest multicellular organisms. Fibronectin is specifically localized on the surface and on the substrate in the immediate vicinity of some, but not all, dissociated Microciona prolifera cells, suggesting that the expression of fibronectin in this organism might be dependent on cell type and/or developmental stage. Fibronectin has been partially purified and characterized from intact Microciona prolifera tissue on the basis of its immunological and biochemical properties.