Electron microscopic studies on Borrelia duttonii in infected mice

To reveal the dynamic status of Borrelia duttonii in infected animals, kidney, liver, and spleen of mice were surveyed three days after inoculation of the organisms by a transmission electron microscope. Following observations were informative on the profiles of B. duttonii in the organs. (1) The borreliae were seen in all the organs observed, in kidney, liver, and spleen. (2) The borreliae were localized in various kinds of blood vessels including the sinusoidal or Disse's space. (3) A number of organisms attacked to the surface of the erythrocytes, but none were found in the cytoplasm of circulating erythrosytes. (4) The borreliae were found in phagocytic cells such ad neutrophils, macrophages and endothelial cells, but none was found in the sytoplasm of hepatocytes or epithelial cells of uriniferous tubules. (5) The organisms in macrophages were localized either in the phagosomes or in the phagocytized erythrocytes. (6) B. duttonii in the capillary lumen showed normal morphology, while those in phagocytes or in phagocytized erythrocytes showed a degenerated feature. The above findings suggested that injected B. duttonii proliferated in the capillary luman, and some od them were engulfed by ohagocytes by themselves or thgether with erythrocytes. It was also suggested that a few borreliae might be released from the phagocytes and proliferate again in the capillary luman.