title: Periodic, multimodal distribution of granule volumes in mast cells.
abstract: The areas of 2327 mast cell granules in transmission electron micrographs of sections of peritoneal mast cells from adult rats were measured by digitized planimetry. A histogram constructed using equivalent volumes calculated from the measured areas assuming approximation of the granules to spheres showed a periodic multimodal distribution in which the modes fell at volumes that were successively larger integral multiples of the volume at the first mode. Application of a moving-bin technique to the data confirmed the presence of the modes. We propose a mechanism of fusion of unit sized granules to account for the multimodal distribution. The presence of pear- and dumbbell-shaped granules in mast cells is consistent with this mechanism.
mesh_terms: D000818:Animals; D003594:Cytoplasmic Granules / Q000648:ultrastructure*; D008297:Male; D008407:Mast Cells / Q000648:ultrastructure*; D010507:Periodicity; D051381:Rats