The fine structure of human liver cells was studied with electron microscope in biopsy specimens of embryonal livers, adult livers, and livers of hepatitis. The results.obtained may be summarized as follows:
1. Though endoplasmic reticulum in the liver cells were long and flatt in the normal embryo, they were abundand and vesicular in the adult, and were destructed in the hepatitis.
2. Cristae mitochondriales were more prominent in the liver cells of hepatitis, compared those in the embryonal and adult liver cells.
3. In the embryonal liver cells, cytoplasmic granules were demonstrated to advantage.
4. In liver cells of hepatitis, granules and vesicles were increased in number.