“…All these factors make isolation of the organism from ϐield samples even more difϐicult. Currently, the most frequently used techniques for M. hyopneumoniae diagnosis are the histological analysis of affected tissues, immunohistochemistry (IHC) and, more recently, polymerase chain reaction (PCR) (Mattson et al 1995, Calsamiglia et al 1999, Ribeiro et al 2004, Thacker 2004, Otagiri et al 2005. Samples used for histological techniques are routinely kept in a 10% formalin solution and the subsequently embedded in parafϐin (formalin-ϐixed, parafϐin-embedded -FFPE) (Srinivasan et al 2002, Coura et al 2005, Delfour et al 2006, Ferrer et al 2007, and pathology laboratories keep large collections of FFPE samples, allowing important retrospective studies using histological analysis (Ferrer et al 2007).…”