ones remarkably at the ¢ ritical stage. Though the curves of erythrocytes and platelets lay on normal Japanese ones alter 2 years, the curve of leukocytes still displaced slightly ta the left of normal one even aiter 6 years. +. Cytovenctics Follow-up of chromosonm. observations in blood cells has been performed since 1964. Even 20 years after exposure, cells with chromosome abnormalities (both Cu and Cs cells) exist in the peripheral lymphocytes with much higher frequencies than in general population. The frequency of Cu cells (dicentrics + rings), however, was decreasing. Onthe other hand, Cs cells remained fairly constant in the frequency of around 2%. The frequencies of the chromosome G abnormalities were found to be corresponding to the severity of injuries indicated by minimum leukocytes count at the critical stage. Inthe bone marrow, cells with chromosome abnormalitics {Cs cells } occurred rather constantly with frequencies of more than 2% in all the 4+ times of samplings carried out 13-17 years after cxposure., 3. Spermatopoicsis Number of spermatozoa decreased about 2 months after exposure, and 1z00spermia was found. Both fall of motility and morphological abnormalities of spermatozoa were also observed. recovery were noticed about 2 years alter cxposure. the patients got healthy children. Indications of Then most of — The testicle of the fatal case, which dicd 206 days alter cxposure, showed cxtremely reduced spermiatapoicsis, 6. Other findings Slight disturbances of the liver function were found in a few cases at the time of hospitalization. Later it became more obvious. “One of the fishermen, who revealed remarkable hernatological disturbances, died from liver damage. During follow-up studics elevated values of - 92 - :