DIFFERENTIAL REACTIVITY OF STRUCTURAL COMPONENTS OF EOSINOPHIL LEUKOCYTE GRANULES AS REVEALED BY ETHANOLIC PHOSPHOTUNGSTIC ACID

After glutaraldehyde fixation and ethanolic phosphotungstic acid (E-PT A) treatment before embedding, thin sections of rat bone marrow and la rge intestine showed a characteristic pattern of electron opacity in e osinophil leucocyte granules. In both mature eosinophils and precursor cells, the matrix appeared highly contrasted while the crystalline co re revealed no electron density. Additional treatment of sections with uranyl acetate did not modify the contrasting pattern of eosinophil g ranules. The absence of electron dense reaction in the crystalline cor e after E-PTA treatment seems to originate from removal of core compon ents. The selective reactivity of the matrix toward E-PTA could be a v aluable ultrastructural marker for studies on the differentiation of s pecific granules along the maturation of eosinophil leucocytes.