Effects of Mycoplasma hyopneumoniae and M. hyorhinis on ependymal cells of the porcine lateral ventricles as observed by scanning and transmission electron microscopy.

Porcine lateral ventricular ependymal cells were used to study the effects of infection with Mycoplasma hyopneumoniae and M. hyorhinis on the central nervous system (CNS) of pigs. After cerebral or cerebrospinal inoculation, cellular sequential changes were observed by scanning (SEM) and transmission (TEM) electron microscopy. Strains of M. hyopneumoniae and M. hyorhinis were recovered from infected tissues at 1 and 3 weeks postinoculation. The mycoplasmas caused lesions of ependymal cells. Degenerative processes ranged from loss of microvilli and cilia to membrane breakdown and invasion of cells. The results suggest that mycoplasmas cause ependymal cytopathological effects similar to those that they cause in ciliated epithelial cells of the trachea and lung. Both M. hyopneumoniae and M. hyorhinis may be involved in the pathogenesis of certain ill-defined CNS disorders in swine. The potential value of using both SEM and TEM to observe the effects of mycoplasmal infection on ependymal cells of the porcine CNS was demonstrated.