II. APLASIA OF MARROW AND FATAL INTOXICATION IN DOGS PRODUCED BY ROENTGEN RADIATION OF ALL BONES

Area of Science:

• Radiation Biology
• Hematology
• Pathology

Background:

• Acute radiation exposure can lead to severe systemic effects.
• Understanding the physiological response to radiation is crucial for medical management.

Purpose of the Study:

• To document the consistent pathological findings following acute radiation exposure to the bony skeleton.
• To characterize the temporal progression of radiation-induced toxicity.

Main Methods:

• Observation of clinical and hematological parameters in subjects exposed to a specific dose of heavily filtered radiation.
• Gross and microscopic examination of organs and tissues post-exposure.

Main Results:

• Fatal intoxication developed 8-9 days post-radiation.
• Profound leukopenia (≤200 WBC/c.mm.) occurred 5-6 days post-exposure, persisting until death.
• Platelets disappeared from blood smears the day before death.
• Extensive capillary hemorrhage was observed in all organs.
• Spleen and lymph nodes showed significant reduction in substance and germinal centers.
• Red cell hematocrit decreased from ~50% to ~40%.
• Bone marrow was depleted of hematopoietic cells, with only stromal elements and phagocytes remaining.

Conclusions:

• Acute radiation exposure to the bony skeleton induces a predictable and fatal syndrome.
• The observed hematological changes, particularly leukopenia and platelet loss, are critical indicators of radiation toxicity.
• Widespread hemorrhage and bone marrow aplasia are key pathological hallmarks of this acute radiation response.