Lipid granules have been found in the cytoplasm of odontoblasts and in the odontoblastic extensions within the dentinal tubules. It is suggested that these granules represent specific activity on the part of the normal cell as well as an increase in number after injury. While they are not limited to occurrence within the vacuoles in the cytoplasm of the odontoblasts, the relationship of the granules to the vacuoles suggests that the vacuoles are also a part of the physiologic activity of the adult odontoblasts.