Changes in the surface coats of neoplastic human breast epithelium.

Phosphotungstic acid at low pH has been used as a section stain to make visible the surface coats of benign and malignant epithelial cells from human breast biopsies in the electron microscope. For this purpose, tissue is fixed in glutaraldehyde and embedded in the water-soluble plastic glycol methacrylate. Duct epithelial cells from all the biopsies containing benign tissue showed consistently more phosphotungstic acid-positive material at their surfaces than did the malignant cells. These results from an in vivo system are consistent with the observations of others, who have shown that there are lower amounts of sugars at the surfaces of transformed cells in culture. Thus, alterations of surface polymers, such as glycoproteins, may be important in the development and maintenance of the altered growth properties of malignant breast epithelial cells in vivo.