a T. KUMATORI subjects, i.e. Hiroshima cases, Marshallese, and cases exposed by reactor ac- «dey at weeip 68 Hematological F cidents (HEMPELMaNetal., 1952 ; AmaNo, 1953 ; Cronkite et al., 1956 ; Hastercix and Marineuul, 1956; Gusxova and Batsocotov, 1956; Anprewset al., 1961 ; Jammet, 1961), it is noted that all these cases similarly revealed the minimal value at about one month after exposure. 5. Bone Marrow The bone marrow was aplastic at the critical stage in severe cases, which showed remaining and proliferation of plasmacells and reticulum cells. Figure 3 shows the bone marrow of oneof the severe cases. Comparing with normal eee alarapatren AAEM METI ag Rimr RL. 6a Rime nee . kocytes of Bik Fig. 4 oeumulative). Te QR SO ane ete we a Te See me eg eR oR Pe woe woe Ry aw Me rT ~ eo: - a. feat * . ho .* en Poe e+ oe gos iv. . «Foye 8 ae PF oe * - . Set “ere . > - . = vot [0 eer _* oat eg oth yor mn. Sgdemer Ne Fe 5 i - S ~*. a * Fee 4) |e e ‘a 7 : . t bk oo vot gy e PEE wee et -. fet Ce thce ES Fig. 3 - rege = . eee ; 4 wD, oe >. "ge y = . . ° oy o ~%-. - se: hte . . . oho -- —s * “4 : : Se a aere * a vd Tew. ee Me as Po . “ «+. 9 é i.+ . * WP . Hd wr * nd os oe . ~ ow ant. , ‘ges -—_ . Wt: . wr . aut s tNSO nod . 3 fle Sq = >» ~ ae * ” otae. x ae ts o te[o0s7,7 Nos Pee as “ae > ~ Jy > * ~*~ 4 “ eel. -“ ~Wor"s —- ot Bone marrow of one of severe cases at 5th week. bone marrow a lack of bone marrow cells was observed. With the beginning of recovery, aplastic marrow changed to hypoplastic and then turned In some cases, recovery was not complete 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 normalpersons. 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 leuko- cytes. 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 wasstill displaced slightly to the left ad Feet in Fig. 5 Changes< cytes. neutrophils of normal jap chat e Morphological and Functional Changes Several morphological abnormalities were observed: nuclear debris of the curve app in the cumula! pepe SGpindgsi 6. prepa even after one year. In less severe cases, the bone marrow was notaplastic but hypoplastic or in a type of maturation arrest even at thecritical stage. whan + into a type of maturation arrest. However, the changes of are represent: A small i of erythroble 10 years. Cytogen results are S 1. The