The authors thank Prof. Dr. Norberto P. Lopes for the HRESIMS analyses. This research was supported by grants from FAPESP (BIOprospecTA Proc. 04/07942-2, 06/57122-6), CNPq (472870/2004-1), and INCT-Imunologia. M.S.P., R.R.N. and C.F.T. are researchers for the Brazilian Council for Scientific and Technological Development (CNPq). “
“Envenomations by freshwater stingrays are characterized by intense pain and pathological alterations

at the injury site. These include edema, erythema and, in most cases, necrosis ICG-001 (Haddad et al., 2004). The damage is caused by the stinger located in the back of the stingray tail, which is used by the animal to defend itself (Charvet-Almeida et al., 2002 and Garrone Neto et al., 2007). Integumentary and glandular tissues cover the stinger where the toxins are produced (Pedroso et al., 2007). The anatomical regions most afflicted in injuries caused by stingrays are the hands and feet (Haddad et al., 2004, Brisset et al., 2006, Lim and Kumarasinghe, 2007 and Garrone Neto and Haddad, 2009). Lethal injuries rarely APO866 purchase occur except for cases where the stinger reaches vital organs (Isbister, 2001 and Garrone Neto and Haddad, 2009). Specific antivenom is not available for the treatment of stingray injuries, and the therapeutic approach is based on the use of analgesic and anti-inflammatory drugs, hot water to relieve the excruciating pain and antibiotics to prevent secondary

infection (Haddad et al., 2004, Clark et al., 2007, Dehghani et al., 2009 and Garrone Neto and Haddad, 2010). In Brazil, the distribution of freshwater stingrays has gradually

increased due to environmental alterations mainly represented by the construction of hydroelectric power plants (Barbaro et al., 2007, Garrone Neto et al., 2007 and Garrone Cytidine deaminase Neto and Haddad, 2010). The ability of the extracts obtained from the tissue covering the stingers of Potamotrygon falkneri to cause toxic activities such nociception, edema, myotoxicity, necrosis and lethality has already been reported ( Barbaro et al., 2007). Many enzymes such as proteases and hyaluronidase were detected in the extract obtained from Potamotrygon freshwater stingray ( Haddad et al., 2004, Barbaro et al., 2007 and Magalhães et al., 2008). In addition, peptides effective in the microcirculatory environment were isolated from Potamotrygon gr. orbignyi venom by Conceição et al., 2006 and Conceição et al., 2009. The histopathological features after injection of toxins extracted from the stingray stingers are practically unknown. The aim of this study is to characterize the main histological alterations in mice skin induced by experimental envenomation using extracts from the tissue covering the stingers of P. falkneri. Swiss mice (18–20 g) were provided by the Butantan Institute Animal House. Animals received food and water ad libitum. Specimens of P.