Fine Structure of the Specific Granules of the Mast Cells from Human Bone Marrow

Abstract

The structure of the specific granules of human mast cells has been studied by electron microscopy in sections of bone marrow obtained by sternal aspiration, and the crystalline structure has been analysed by microdensitometry. The repeat of both the lamellar and the scroll structure has been approximately 120Å. The spacing between dense bands of a honeycomb pattern on hexagonal array was also about 120Å. It is suggested that the specific granules are composed of electron dense particles closely packed hexagonally. From these results the crystalline patterns of the specific granules could be interpreted as interference patterns of electron dense particles in a hexagonal closet packing. It is further suggested that the scroll structure is formed by the condensation of homogeneous content of the granules and the lamellar crystalline structure is probably formed by regular stucking of the lamellae.