Hematological and Maartnetti, 1956; Gusxova and BatsocoLov, 1956 ; ANprews et al., L961 ; JamMet, 1961), it is noted that all these cases similarly revealed the minimal value at about one month after exposure. Bone Marrow The bone marrow was aplastic at the critical stage in severe cases, which - ’ 2 -ay Ge - . fee aw of my” oot a. ee, S 4 OP ” £ * at -_¢ . Lee \ oops eee ud i ad . '. fo a - ? of * * ar Fig. 3 wen ye a ee ARS ett ° > - 7 a a nt . eee y awe ¢ . . "eye ee 3 Mig > - va —_ —, —~e? se “> so, ef ve e tea Sane : ‘ ™ “wes .* ee “ = CA * awe é geo. “a mm ~ ‘my . Ve eoe > on" ' . 4 . AA, . 4 a : ~~ Was . oi +t ‘te rar Me 7 Bone marrow of one of severe cases at 5th week. bone marrow a lack of bone marrow cells was observed. With the begin- ning of recovery, aplastic marrow changed to hypoplastic and then turned into a type of maturation arrest. In some cases, recovery was not complete even after one year. In less severe cases, the bone marrow was not aplastic but hypoplastic or in a type of maturation arrest even at the critical stage. Morphological and Functional Changes . Several morphological abnormalities were observed: nuclear debris of lymphocytes, binucleated lymphocytes, vacuoles of neutrophils, toxic granulations of neutrophils, degenerative changes of blood cells, mitotic abnormalities of erythroblasts, etc. Motility and phagocytosis of neutrophils decreased remarkably. After one year, in some cases these functions were still lower than in normal persons. o Qtumulative). ‘ . ee ote fs ry ee ~- e tote. FOLLOW-UP STUDIES As above mentioned 16 to 18 fishermen have been examined on an annual basis. Figure 4 shows the changes of the cumulative distribution curves of leukoevtes. The curve of critical stage appeared displaced far to the left of the normal curve, and gradually approached normal values. However, the curve of the 6th year was still displacedslightly to the left Fig. 5 Changes ir cytes. neutrophils t c 2 asthe. Seshoetqnareehgnet Pe . non ° 3% “e005 te, -" ves Bh oe *.. . Leukocytes of B ciamera 2g ak ates vs -. 2 Th en US : Fig. 4 cm ee showed remaining andproliferation of plasma cells and reticulum cells. Figure 3 shows the bone marrowof oneof the severe cases. Comparing with normal 2 ab ad pte 5. eee subjects, i.e. Hiroshima cases, Marshallese, and cases exposed by reactor ac~ cidents (HEMPELMAN et al., 1952 ; Amano, 1953 ; Cronkite et al., 1956; Haster.ix ee T. KUMATORI OOTPebb i eke “ 68 of normal Jap. the curve apr jn the cumula However, the changes © are represent A small of erythrobl. 10 years. Cytoget results are £ 3. The