Electron Microscopic Studies on the Mast Cells from Human Bone Marrow

Abstract

Mast cells obtained from human bone marrow have been studied by an electron microscope. The cells are usually round or oval and contain a nucleus possessed features typical of nuclei in most other cells. There are one or more nucleoli within the nucleus and the dense chromatin blocks usually attach to the inner nuclear membrane. The Golgi complex is frequently located at or around the indentation of the nucleus. Mitochondria, round on oval in profile, contain a few cristae. Microvilli are observed on the surface of the cell membrane. There are a number of specific granules in the cytoplasm of the cells, which are usually round in shape,0.5-0.7μ in diameter, and surrounded by a limiting membrane. Within the granules five kinds of structures have been observed; (1) homogeneous structure, (2) granular structure, (3) scroll structure, (4) lamellar crystalline structure, and (5)hexagonal crystalline structure. Sometimes a number of vacuoles are observed within the cytoplasm. Some of the specific granules are in close contact or in fusion with the vacuoles.