Ultrastructural comparison of basophilic leukocytes and mast cells in the guinea pig

Abstract

AbstractDifferences in the ultrastructure of basophils in the bone marrow reflect transition from early to late stages of cell development. Mast cells in the trachea, stomach and duodenum lack such developmental changes, but one cell encountered in mitosis indicates a low rate of replication by apparently mature cells. Mast cells differ from basophils in shape and in the structure, shape, and position of the nucleus. The Golgi complex clearly participates in granulogenesis in early basophils but not in late basophils or mast cells, and in mast cells appears associated with rough coated vesicles and mitochondria. In basophils precursor granules mature into a homogeneous granules population. The more numerous, smaller, rounder, granules of the mast cells differ also in varying widely in structure and not evidencing a clear maturational sequence. Increased density of mast cell granules apparently correlates with decreased size and increased indentation by a lucent focus and with the presence of lucent vacuoles in the cytoplasm. Laminated, crystal‐like foci replacing the thread‐like component in the periphery of some granules appear rigid and resist the indentation deforming the granule elsewhere. Mast cells of the adult differ from those of fetal guinea pigs in lacking the concentric lamination and having more dense granules. Many mast cells reveal several small, dense bodies which apparently constitute a second granule type, and often occupy the lucent indentation of the large granule.