Mycoplasma meleagridis-induced lesions in the tarsometatarsal joints of turkey embryos

Mycoplasma meleagridis (MM) has the ability to cause bone deformity in turkey poults. However, few pathological lesions have been described and no evidence of MM-induced damage to the bones has been shown. In this study, 17-day-old turkey embryos were inoculated with MM into the allantoic cavity. On the 27th day, eight of the 22 embryos presented with curved toes. Scanning electron microscopy of the tarsometatarsal joints showed fissures in the cartilage. Histological sections of the joints revealed only the infiltration of cells with eosinophilic granules. Immunohistochemical staining (IHS) showed the presence of MM in the aggregates of the bone marrow cells and the cells with eosinophilic granules. Some of these cells were harvested by laser capture microdissection (LCM), lysed, and used as template DNA. With a pair of MM-specific primers in a conventional polymerase chain reaction (PCR), a gene product was amplified, and it comigrated with the MM DNA, which indicates that these captured cells contained MM DNA. Thus, this research shows that inoculation of MM into the turkey embryos produced joint lesions and caused cellular infiltration within the bones.