H. A. RAGAN, P. L. HACKETT, B. J. MCCLANAHAN AND W. J. CLARKE 
923 
cytopenia, neutropenia and lymphopenia. Their 
offspring manifested much more severe hemato- 
poietic depression, so that by one year of age 
their leukocyte and platelet values were approx- 
imately 50% that of control animals, and deaths 
occurred at about three years of age. Many ani- 
mals in this group developed hematopoietic neo- 
plasia which will be detailed below. 
In the 1, 5 and 25 jitCi/day levels, there have 
been no definitive changes observed to date in 
the circulating cellular elements of either origi- 
nal or offpsirng pigs. There was a suggestion of 
a slight depression in neutrophil values in the 
25 /LiCi/day group, but this observation awaits 
confirmation by statistical analysis. As the ani- 
mals in these groups age beyond 5 years, evalu- 
ation of hematologic data becomes complex be- 
cause of complications from uterine tumors, 
oral infections, and other causes of leukemoid 
reactions. 
In the uterine-milk exposure study, the pe- 
ripheral blood values of animals kept on 125 
/u,Ci/day have been consistent with those pre- 
viously observed at that level. Cellular elements 
of those exposed in utero only, milk only, or in 
utero and milk only, have not been different 
than those of the controls (Figure 2). Exami- 
nation of aspirated sternal bone marrow when 
these animals were 38 months of age revealed a 
shift to the left in the maturation curves of 
both the erythroid and myeloid series in those 
animals that continue to ingest ^^'Sr (Figures 3 
and 4) . 
PERIPHERAL B LOOD - -U TE R I NE -M I L K STUDY 
AGE, MONTHS 
Figure 2.— Peripheral Leukocyte and Platelet Values of Miniature Swine in the Uterine-Milk Exposure Study. 
