Ultrastructural study of satellite lymph nodes in syphilitic rabbits

In an electron microscopy study of lymph nodes from syphilitic rabbits plasmablasts and plasma cells were unequivocally identified in germinal centres. Up to 20% of the plasma cells possessed unusual cytological features. Paracortical hypoplasia was shown to be associated with actively phagocytic histiocytes. These findings may reflect morphological correlates of the aberrant immune regulation which has been observed in infection with Treponema pallidum.