Vascularization induced in the cheek pouch of the Syrian hamster by tumor and nontumor substances.

We tested fresh amelanotic and dry amelanotic melanoma tissue, gelatin, embryo and adult connective tissue, fresh and dry liver, fibrinogen, fibrin, pouch membrane, starch, dry hamster embryo and placental tissue, and glycogen in the transparent cheek pouch chamber of the Syrian hamster to explore the specificity of tumor angiogenesis and the mechanism that may selectively inhibit proliferation of blood vessels in the pouch membrane. Differences between the proliferations induced by tumor and normal tissues, various proteins, and polysaccharides were qualitative as well as quantitative. The glucocorticoid 6 alpha-methylprednisolone (MPS) decreased and sometimes totally inhibited the vascularization phenomenon. Dry tumor tissue induced capillary proliferation in seven of eight chambers 3 days after surgery; two of seven chambers of MPS-treated animals showed a reaction 10 days after the operation. MPS suppressed (in some cases only partially) capillary proliferation in chambers with implants of adult connective tissue, fresh liver, starch, or glycogen.