Analysis of the Radiation-Induced Loss of Testes Weight in Terms of Stem Cell Survival

摘要

The proportion of radiation-insensitive tissue in the testes of the C57L mouse was determined to be 36.9% of the normal nonirradiated testes weight. The weights of testes of these mice at 28 days after various doses of irradiation were analyzed by subtracting out the radiation-insensitive weight and calculating the surviving fraction (S/So) of radiation-sensitive weight. The logarithm of S/So could be fitted linearly to the radiation dose, indicating an exponential tissue-loss process with a D37 for 250 KVp X-rays of 78.9 rad. The D37 for testes weight loss from sission-neutron irradiation was 21.0 rad, indicating a relative biological effectiveness ratio (R.B.E.) for fission neutrons of 3.75. Treatment of mice with AET (2-aminoethylisothiouronium bromide hydrobromide) 15 minutes before irradiation with X-rays increased the D37 to 119.6 rad, indicating a protection ratio of 1.5 for AET. Treatment of mice with Piromen (pseudomonas polysaccharide) 24 hours before irradiation had no effect on the D37 for testes weight loss. Irradiation with X-rays at 2.8 R/min gave the same D37 for testes weight loss as irradiation at 14 R/min. The data indicate that loss of weight of the testes after irradiation reflects the survival curve of the germinal cell layer of the testes. (Author)