Abstract
Periodic Acid-Shiff (PAS) reaction of neurtophils in the peripheral blood of the eel, Anguilla japonica was investigated. PAS-positivity of neutrophils in healthy fish was characterized by diffused reddish stainning in the entire cytoplasm. The PAS positive substance of this cell was identified as glycogen, because it was completely spoiled by salivary digestion. Following injection of eels with bacteria, the number of neurtophil in the peripheral blood was increased, and there was an apparent change in the PAS-positive substance. Based on the morphology of the PAS-positive substance in the cytoplasm, neutrophils were divided into five types: Type I-weak positive with diffused stainning. Type II-strong positive with diffused stainning. Type III-strong positive with numerous fine granules. Type IV-strong positive with numerous coarse granules. Type V-strong positive with massive blocks. Distribution of the adove mentioned types in the peripheral blood was examined at regular intervals after injection of the whole cells of bacteria, sonic extract of bacteria and culture filtrates. In the fish inoculated with bacteria, there was a remarkable increase in type III and type IV cells after 24 hours of injection and type V cells increased sharply in the moribund fish. In the case of eels inoculated with sonic extract of bacteria there was an increase in type III and type IV cells, whereas in the eels inoculated with culture filtrates, type III cells only increased. Eels injected with irritant substances other than bacteria did not show any significant changes in the type distribution of neutrophils.
