Vascular and necrotic tumor fractions after EMF treatment. A. Therapeutic EMF on the percent of tumor area immunohistochemically positive for CD 31 (a measure of tumor vascular volume fraction). The mean CD 31- positive area of each tumor treatment group is shown in the scattergram. Statistical analysis (ANOVA followed by SNK post-hoc test) revealed the mean of CD 31 positive area of control group # 1 to be significantly greater than of treatment groups 3 to 8 and groups 3 and 4 to be significantly greater than group 6. B. Significant, one phase decay relationship between CD 31positive area and the necrotic fraction of tumors after EMF treatment.