Cathepsin B containing cells in the rabbit mesentery during invasion of V2 carcinoma cells

Localization of cathepsin B was studied in the rabbit mesentery during invasion of V2 carcinoma cells. Cathepsin B was visualized immunohistochemically by using monospecific sheep antibodies and the avidin-biotin-peroxidase complex (ABC) method. Horizontal and vertical semithin Epon embedded sections of stained mesenteries showed that histiocytes always displayed the strongest staining reaction independently of the presence of V2 carcinoma cells. Fibroblasts, mesothelial cells and the invaded V2 cells were less stained. Strongly stained peritoneal monocytes were frequently found on the surface of the mesentery in association with tumor foxi. The role of these various cathepsin B containing cells with respect to extracellular matrix degradation during tumor invasion in the mesentery is not clear; some aspects of this problem are presented in the discussion.