DEGRADATION OF PERITONEAL BASEMENT MEMBRANE BY METASTASIZING TUMOR CELLS-AN IMMUNOELECTRON MICROSCOPIC STUDY-

Abstract

The degradation of murine peritoneal basement membrane following metastasis of Ehrlich ascites tumor cells was studied by immunoelectron microscopy using antibodies for laminin and type IV collagen. Immunostaining for these two membrane components revealed a three-layered structure of the normal basement membrane. Soon after the intraperitoneal injection of tumor cells, submesothelial connective tissues were invaded and mesothelial cells were exfoliated by the tumor cells. The basement membrane of the host cells was observed to undergo dispersion of its membranous components facing the tumor cell, suggesting an initial chemical dissolution mechanism. Subsequently, cytoplasmic processes of the tumor cell invaded the basement membrane of the host cells, tumor cells forced themselves into the connective tissue, and fragments of the basement membrane were pushed aside and scattered. These steps have the appearance of a physical breakage process. The tumor cells underwent constriction as they penetrated through the basement membrane, and the adjacent basement membrane remained intact. These results suggest that chemical dissolution followed by physical breakage occur in the basement membrane under attack by tumor cells.