The ultrastructure of eosinophil granules of the black-necked crowned crane.

The fine structure of the granules of circulating eosinophil leucocytes was studied in five adult black-necked crowned cranes. The interna within these granules showed various crystalline arrangements. Optical diffraction patterns of the crystals revealed linear arrangements measuring 6.2 and 3.8 nm and often, when these arrangements were superimposed, a hexagonal pattern was observed. Bundles of microfilaments measuring 5-7 nm in diameter were found frequently in crystal-containing granules. Staining with phosphotungstic acid (PTA) and various other cytochemical procedures gave results similar to those obtained previously in the shag and the duck. The PTA stain and peroxidase reaction product were found only in the externum of the granules whereas the acid hydrolases, acid phosphatase and arylsulphatase were located within the crystalline matrix and in or between the microfilaments. As with shag eosinophil granules, those of the crane did not appear to contain histone arginine and in this respect they differed from those of the duck and the fowl.