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.