Effects of X‐irradiation on mouse testicular cells and sperm chromatin structure

Abstract

The testicular regions of male mice were exposed to x‐ray doses ranging from 0 to 400 rads. Forty days after exposure the mice were killed and the testes and cauda epididymal sperm removed surgically. Flow cytometric measurements of acridine orange stained testicular samples indicated a repopulation of testicular cell types following x‐ray killing of stem cells. Cauda epididymal sperm were analyzed by the sperm chromatin structure assay (SCSA), a flow cytometric measurement of the susceptibility of the sperm nuclear DNA to in situ acid denaturation. The SCSA detected increased susceptibility to DNA denaturation in situ after 12.5 rods of x‐ray exposure, with significant increases following 25 rads. Abnormal sperm head morphology was not significantly increased until the testes were exposed to 60 rads of x‐rays. These data suggest that the SCSA is currently the most sensitive, non‐invasive method of detecting x‐ray damage to testicular stem spermatogonia.