Ultrastructure of Human Basophils

Abstract

Basophilic leukocytes (Fig. 12) can be distinguished from mast cells in humans by ultrastructural criteria (Dvorak 1978, 1986a; Dvorak et al. 1974, 1976a, b, 1980e, 1981a, b, 1982, 1983a, c, d, 1985b; Dvorak and Dvorak 1975; Findley et al. 1981; Fox et al 1984; Galli et al. 1983, 1984; Ishizaka et al. 1985; Peters et al. 1987). These diagnostic features include polylobed nuclei with a condensed chromatin pattern, surface architecture which consists of irregular, broad, cytoplasmic protrusions, cytoplasmic glycogen, and granules. In mature basophils, the Golgi apparatus is inconspicuous and membrane-bound ribosomes are rare. Free ribosomes, mitochondria and cytoplasmic vesicles and filaments are present. Lipid bodies can be found in basophils. Basophil granules are larger and less numerous than their counterparts in mast cells. These membrane-bound structures are filled with dense particles (Fig. 13A) that vary in the density of packing within granules. Some granules contain focal collections of membranes that may enclose some granule particle contents (Fig. 13B). These membrane collections can sometimes resemble some scroll patterns found in human mast cells. When all nuclear and cytoplasmic criteria are considered, human mast cells can, however, be readily distinguished from human basophils.