Figure 4.
Histological depiction of cellular changes in the ablation zone on H&E-stained sections (A) showed 3 distinct areas of unviable tissue: 1) the TFZ immediately surrounding the fiber, which was heat fixed and structurally intact; 2) the CNZ, which was a pale rim of coagulation necrosis surrounding the TNZ; and 3) the MZ, which was a less distinct thin band with edema in the interstitial tissue. See Figure 5 for higher magnification of the area within the rectangle (A). The chromogen diaminobenzidine tetrahydrochloride (DAB) is brown and allowed visualization of vWF immunolabeling (B). vWF immunostained endothelial cells. Immunopositive staining in the blue rectangle was endothelial cells lining an intact blood vessel. Abnormally excessive vWF immunostaining was seen adjacent to the laser tract as a result of traumatic injury, and in the CNZ and MZ due to thermally injured blood vessels resulting in edema derived from leakage of plasma and plalelets into the interstitial areas. LT= laser tract; TFZ= thermally fixed zone; CZN= coagulative necrosis zone; MZ= margin zone; and UZ= untreated zone. Bar = 1 mm.