An experimental animal model for the study of human scirrhous carcinoma

Scirrhous-like carcinomas were induced by the inoculation of cloned mouse mammary carcinoma cells into the cleared fat pads of BALB/c mice. The inoculated cells induced palpable tumors in 100% of the animals within 60 days. The epithelial cells in vivo grew in rows and clusters and were attached by short developing desmosomes. Microvilli and organelles were scarce; intracisternal type A particles were observed in all the epithelial cells. Carcinoma cells invaded the dermis and muscle. The stroma was formed by morphologically normal fibroblasts and large masses of collagen. No virus particles were observed budding from the epithelial cell surface or in the stromal fibroblasts. The similarities between the scirrhous-like carcinoma in BLAB/c mice and the juman scirrhous carcinoma suggest this animal system as a model for the study of the human disease.