Cells cultured from calf ligamentum nuchae produce extracellular microfibrils identical to those of intact elastic tissue as determined by ultrastructural appearance, degradative enzyme susceptibilities and amino acid composition. A method to isolate large amounts of the microfibrillar component using fluorescein mercuric acetate is described. The cultures do not appear to synthesize the amorphous component, elastin, in that radioactive desmosine and isodesmosine were not detected after incubating cultures with labeled lysine nor was elastin seen ultrastructurally.