Fig. 4.

Histologic images of treated and control tumors from a representative mouse (M7) 24 hours after PDT. An inflammatory response with edema was observed in the treated tumor (a), which was not seen within the control tumor (b). The rectangular areas on images (a) and (b) are magnified and shown in images (c) and (d), respectively. On image (c), massive areas of tumor cells were damaged by PDT, and the tissues became necrotic. However, the control tumor cells were intact (d). The laser light was focused approximately perpendicular to the plane of the tissue slice. The two tumors were from the same mouse (M7).