Five primary and 3 established human glioma cell lines were cultured with ascorbate and examined for expression of extracellular matrix components. All lines except C6 expressed collagen as assessed by silver impregnation, immunofluorescence and lectin staining and expressed laminin and fibronectin. None expressed a lectin marker for endothelial cells. Both epithelial and mesenchymal collagens were expressed. While extracellular components of glioma lines resembled those of fibroblasts more closely than other cell types, subtle differences between gliomas and fibroblasts were present. These included more laminin and collagen type-IV antigenic reactivity and more 11-12 nm diameter extracellular fibrils from individual gliomas, and slight differences in spectra of low-molecular-weight extracellular proteins assessed by gel electrophoresis. One primary and two established glioma lines analysed for DNA content were aneuploid in contrast to diploid fibroblasts. Simultaneous expression of mesenchymal and epithelial markers suggests a dual differentiation potential of glioma cells. Results do not support an endothelial origin for cells cultured from gliomas.