Ultrasonically induced nuclear aberrations in an in vitro multicellular tumour system

Chinese hamster V-79 cells, attached to an acoustically transparent membrane and EMT6/Ro mouse mammary sarcoma cells as small multicellular spheroids or in suspension, were exposed to therapeutic intensities of 1 MHz ultrasound (0-10 W/cm2) and examined for the production of atypical nuclear or chromosomal aberrations. In the monolayer configuration no abnormalities occurred. In multicell spheroids or suspension cells 3 classes of abnormalities were found: (1) pyknotic/irregular nuclei; (2) lysed nuclei with extruding nucleoplasm; and (3) agglomerations which have an irregular shape and "fused" morphology similar to that which has been reported for plant tissues (Cataldo et al, 1973).