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An extensive study has been made of the cellular changes occurring in mouse liver as a result of exposure to intense, focused ultrasound. In this study a broad range of doses of continuous and pulsed ultrasound have been employed. Groups of animals have been sacrificed at different times after irradiation and the exposed tissue examined, a number of cytological and histochemical techniques being used. Evidence of a selective action of pulsed ultrasound has been found both immediately after irradiation and at later times. This localized action is related to the histological organization of the liver and appears to selectively affect the parenchymal cells. Data on the relation of the amount of hepatic injury produced by ultrasound to several dosage parameters will be presented. The observed effects of ultrasonic action will be discussed in terms of the hepatic architecture and cell structure. [ABSTRACT FROM AUTHOR]

Previous studies have shown that the frequency distribution of mice with hepatic lesions produced by ultrasound is strongly dependent upon heating effects. Alterations in cell fine structure by focused 1-Mc/sec ultrasound have been examined in an attempt to determine the nature of subcellular changes characteristic of dose levels producing little or no tissue heating. Liver was irradiated in situ, the animals sacrificed immediately, 1, and 24 h later, and the exposed tissue examined with the light and electron microscopes. While all subcellular components were altered by ultrasound at high dose levels, the endoplasmic reticulum and mitochondria appeared most strongly affected. Extensive damage to the endothelial cells forming the walls of the blood vessels was also apparent. Pulsed ultrasound, at moderate dose levels, produced a marked, localized disruption of cell fine structure, cytoplasmic organelles in adjacent regions appearing relatively undisturbed. Histochemical and ultrastructural changes indicate that the cytoplasmic membranes involved in glycogen storage are particularly sensitive to ultrasonic energy. The electron-microscopic observations are discussed in terms of several possible mechanisms of ultrasonic action. [ABSTRACT FROM AUTHOR]