Excessive basement membrane material production by epithelial tumors induced by dimethylnitrosamine in rat kidneys

In an experimental series of preneoplastic lesions and neoplasms induced in the rat kidney by dimethylnitrosamine, four of the 54 tumors showed particular morphological features that allowed them to be grouped separately. The leading characteristic of these lesions was an abundant PAS-positive matrix in which the tumor cells were embedded. The demonstration of variable amounts of laminin, heparan sulfate proteoglycan, collagen types IV and V in the tumor matrix provided circumstantial evidence that it consisted of basement membrane material. Since the tumor cells were in intimate contact with the matrix and no fibroblasts were present, it was assumed that the matrix was a product of the tumor cells. Until now, no similar renal tumors have been described in laboratory animals and no human equivalent is known.