Abstract

• Salmonella typhus endotoxin, a lipopolysaccharide constituent of the cell walls of gram-negative micro-organism, is a major cause of the local inflammation, systemic symptom, and shock.
  It recently has been reported the cytokine including tumor necrosis factor and interleukin I as mediators of inflammation and immunity.
  However the mechanism of tissue injury and morphologic change of reticuloendothelial system have not yet been confirmed.
  In the present study, it was aimed to clarify the morphologic changes of reticuloendothelial system, spleen, according to experimental duration by endotoxin administration and the antagonized effect of dexamethasone pretreatment.
  In summary of this study, the initial light microscopic changes after endotoxin administration were phagocytic activity of histiocytes and congestion at 1 hour, followed by germinal center widening due to proliferation of geminal cell at 6 hrs and sinus histiocytic proliferation with focal necrosis at 12 hrs, and variably increased degree of morphologic changes in longer duration.
  Dexamethasone pretreatment of rats suppressed morphologic changes particularly in sinus histiocytic proliferation and local necrosis beginning from 1 hour of experiment.
  Electron microscopic findings were confined mainly pyknotic cell, necrotic debris, and degenerative changes such as vacuolization and electron dense bodies after endotoxin administrations as confirmation of light microscopic changes.