Histologic analysis of rat skin sites injected with TNFα. Skin sites were injected with (A) Tyrode or (B) TNFα (10⁻¹¹ mol/site). After a 4-hour in vivo test period, the skin sites were processed and stained as described in the Materials and Methods. In photomicrographs, examples of eosinophils and mononuclear cells are labeled e and m, respectively. Original magnification × 600.