Figure 7.

Proliferation and angiogenesis in early and late s.c. HaCaT/PDGF-B tumors. 2–3 week-old nodules exhibit intense proliferation (BrdUrd-labeled nuclei, green) and increased vascularization (anti-collagen IV stained basement membranes of blood vessels, in red) in the activated stroma. Epithelial cell layers are vital but slowly proliferating (A). The keratinizing multilayered epithelium of progressively enlarging tumors (13 weeks, B) shows many proliferating (BrdUrd positive) cells in the lower layers, while the adjacent stroma cells are not labeled and vessel density is decreased (T = tumor cells; S = stroma). (Bar = 50 μm.)