98 
CARDIAC MODELS 
far are summarized in this report. Forty swine 
were fed the moderate (SC) diet which does not 
contain propylthiouracil (Table I). These swine 
were x-irradiated twice as in Series I study. 
This experiment was designed to find out if ad- 
vanced coronary atherosclerosis and myocardial 
infarction can be produced in swine without 
using propylthiouracil. The diet was given in 
two divided doses in the morning and in the af- 
ternoon. The amount of calories given per day 
was 4,000. Within two months after the swine 
were put on this diet serum cholesterol levels 
rose to 300-650 mg%. After 8 weeks on the diet, 
two doses of x-irradiation were given with 4 
week intervals. Thirty-three swine received 
x-irradiation twice. Starting from approxi- 
mately 3 weeks after the last x-irradiation, 
Figure 6. — Very low power light micrograph of a re- 
cent myocardial infarct found in one of the severe 
diet-fed, X-irradiated swine. Areas contain pale, 
swollen, partially necrotic muscle cells alternating 
with areas of marked inflammatory cell infiltrate. A 
small area of relatively intact myocardium is seen at 
the far upper right. 
■Hi 
\ 
Figure 7. — An older, healing myocardial infarct with 
large, granular dark areas of calcification. Alternat- 
ing patches of light and dark tissue correspond to the 
various stages of necrosis proceeding to fibrosis. 
Figure 8. — Low power electron micrograph of the en- 
dothelial surface and adjacent intima from a large 
atherosclerotic plaque of a coronary artery in a se- 
vere diet-fed, X-irradiated swine. The intimal cells, 
recognizable as smooth muscle cells, are surrounded 
by collagen and contain a moderate number of lipid 
vacuoles. 
