Crystalloid Structure in Granules of Guinea Pig Basophils and Human Mast Cells

Previous electron microscopic observations on basophils and mast cells revealed the cytoplasmic granules of these cells to contain several different types of structures, including fine particles, lamellae, and whorls (1, 2). In the course of observations on guinea pig marrow and human skin specimens which were fixed first in glutaraldehyde, we have noted a crystalloid structure in both mast cell and basophil granules. MATERIAL AND METHODS The femoral marrow from 300-gm albino guinea pigs was cut into 1-cubic-millimeter blocks and fixed for 1 hour at room temperature in a glutaraldehyde solution prepared by diluting 50 per cent biological grade glutaraldehydc (Fisher Scientific Co.) 1:20 in 0.1 • mixed phosphate buffer, pH 7.4. After washing in isotonic sucrose and in saline the blocks were postfixed for 1 hour at 4°C in 1 per cent osmium tetroxide in 0.1 M phosphate buffer, pH 7.4. Specimens were then dehydrated in alcohols, embedded in Epon according to Luft (3), and sectioned with a Porter-Blum microtome. Gold to silver sections were stained with aqueous uranyl acetate and the lead stain of Karnovsky (4), and examined in a Siemens Elmiskop I. Human skin biopsies obtained with a Hays-Martin punch were processed in a similar manner. OBSERVATIONS AND DISCUSSION A low-power electron micrograph of a basophil from guinea pig marrow is shown in Fig. 1. Var-B R I E F N 0 T E S 973FIGURE 1 Low-power view of a basophil in guinea pig bone marrow, showing nuclear lobes and connecting nuclear strands (N), granules (G), mitochondria, centriole, and vesicular structures of ~adous size. Rectangle indicates approximate area shown at higher magnification in Fig. ~. X ~4,000. FI~VRE ~ High-power view of two granules in the cell shown in Fig. 1. The granule which occupies the lower left half of the illustration shows a honeycomb pattern or hexagonal array with spacing between dense bands measuring approximately 140 A. The smaller granule in the upper right corner shows alternating light and dark parallel bands with similar spacing. X 140,000.