Abstract
Ultrastructure of the erythroblasts in the bone marrow of human adults was studied. Although the knowledge of the stem cells has been increasing, the precise morphology of them is not yet clearly identified in the bone marrow specimen. However, the so-called proerythroblasts and the developing erythroblasts are easily identified under electron microscopic observations by the characteristic features such as the round shape of the cells, almost perfectly round nucleus with unique chromatin figures, polysome formation of a few ribosomes, a number of microtubules and micropinocytic vesicles, and siderosomes.
