Radiosensitivity and life span of dog peripheral blood lymphocytes

Observations made after 48 h of cultivation show that 52% of dog lymphocytes are already in M₂ and 17% in M₃ at that fixation time. Evidently, the large discrepancy observed between man and dog with respect to the yield of dicentric chromosomes induced by an exposure to 200 rad of X-rays and observed after a culture time of 48 h does not correspond to a difference in chromosomal radiosensitivity. There is, indeed, no statistically significant difference between the yield of dicentrics observed in M₁ human lymphocytes (32.0 per 100 cells) and that in dog lymphocytes after correction of the values obtained at 48 h (28.6 per 100 cells). From the observations performed on whole-body irradiated dogs one can estimate that the half-time of dog lymphocytes carrying chromosome aberrations is less than 30 days.