INTERNAL DEPOSITION OF RADIONUCLIDES 83 Fiavure 5.2.--Autoradiograph of tibia of chicken sacrificed 45 days poatdetonation (AND). marrow cavity in this tibia contained dense trabecular bonealongits entire length, a forma- tion not normally found in mammulian bones. There are also two distinct areas of increased density in the trabecular region, which appear as two lines of radioactivity in the autoradiograph. The center of the diaphysis was abnormally thick, possibly because of a failure of the normal resorptive process. No other evidence of a double line of radio- active deposit appeared in the animals studied, except possibly in a sowsacrificed 38 days post exposure (Fig. 5.5). Here a faint deposit of activity in the trabecular bone is noted, separate from the higher level in the epiphysis. Looney (4) has shown that a typical osseous tissue in trabecular space is a characteristic histopathological finding following radioactive