2E). Foci of epidermal erosion and mild acute inflammatory infiltrate as well as round collections of cellular debris in the upper dermis and epidermis were present (Fig. 2F). No hemorrhage was verified and very few blood vessels showed thrombosis. Superficial epidermal bacterial infection was present in this website one of the samples. After 48 h of injection, coagulative necrosis of skin, subcutaneous and skeletal muscle tissue was evident (Fig. 3A). The epidermis and the dermis showed mild acute inflammatory infiltrate and collections of cellular debris, characterizing micro-abscesses (Fig. 3B). Few blood vessels in the

dermis and subcutaneous tissue presented thrombosis. No hemorrhage was verified. After 72 h of injection, the necrotic tissue presented cellular debris

in the form of numerous round collections or diffuse infiltration, constituting a necrotic plaque focally detached from the deep tissue (Fig. 3C). Regenerative hyperplasia of epidermal cells appeared at the lesion borders (Fig. 3D). A mild inflammatory infiltrate was observed around viable blood vessels in the deep subcutaneous tissue. After 96 h of injection, the regenerative hyperplasia of epidermal cells at the necrotic skin border was more evident (Fig. 4A). The coagulative necrosis of the tissue was clear, affecting the skeletal muscle and presenting cellular debris infiltration. In one of the samples the epidermis was missing in some areas and superficial bacterial infection appeared (Fig. 4B). No hemorrhage or blood vessel thrombosis was detected. In animals of the U0126 order Phosphatidylinositol diacylglycerol-lyase control group no evidence of necrosis was noted although mild edema and mononuclear cell infiltration of dermis and subcutaneous tissue were focally present. Moreover, control animals did not show any histological abnormalities in most of the skin, and subcutaneous and skeletal muscle tissue (Fig. 4C,D). There are few reports in literature on the toxic effects of freshwater

stingray venom. Under our experimental conditions, we verified that the tissue extract of P. falkneri could induce necrosis and an inflammatory reaction at the site of injection. These data are in agreement with reports of accidents in humans ( Haddad, 2000, Haddad et al., 2004 and Garrone Neto and Haddad, 2010). They are also in agreement with an experimental model ( Barbaro et al., 2007) demonstrating that necrosis and local inflammation are much more prominent in injuries caused by freshwater stingrays when compared with those caused by marine species. Our histological study demonstrated that necrosis occurs very soon after the exposure; foci of epidermal necrosis with initial detachment from the dermis were detected 3–6 h after extract injection. Moreover, at these times, signs of initial necrosis of skeletal muscle were observed.