Electron Microscopic Studies on the Relation of the Basement Membrane to the Squamous Cell Carcinomas in Animals

Abstract

This study was made to determine whether and how the basement membrane is dissolved and breached in invasive epithelial carcinoma. Tumors were produced experimentally in the left cheek pouch of hamsters by topical applications of DMBA (dimethylbenzanthracene). Invasive epithelial growth appeared in 2 mo. at which time the limit between epithelium and connective tissue became indistinct. Cell membranes of tumor cells near the stroma become conically indented and surrounded by a granular substance. Distinct lines of ribosomes reach the projections from nearby mitochondria. The relationship between basal cancer cells and adjacent capillary walls was usually seen to consist of a thin fringe of cement substance in parallel laminas suggestive of a basement membrane. Some specimens showed conical protrusions of the cytoplasm of cancer cells breaking through the basement membrane and stretching to the capillary endothellum cell.