[The ultrastructure of human eosinophils studied by thin sectioning, rapid-freezing and deep-etching technique]

The crystalline structure of mature human eosinophils were observed, both by an ultrathin sectioning, rapid-freezing and deep-etching (RF-DE) technique. The crystals obtained with thin sectioning show parallel bands or square lattice structure with a periodicity of about 4 nm. By the RF-DE technique, most crystals show a staircase appearance and in the crystal parallel bands are observed with a spacing of about 4.4 nm. A square lattice structure is observed in a few granules. Since biochemical studies have revealed that the major basic protein (MBP) was localized in the crystal, the crystals can be considered to be crystalized MBP. Although it is known that the patients with hypereosinophilic syndrome have more hypodense eosinophils compared with the normal volunteer, no morphological differences was found in the crystals, between these two eosinophils.