EFFECTS OF X-IRRADIATION ON MOUSE TESTICULAR CELLS AND SPERM CHROMATIN STRUCTURE

The testicular regions of male mice were exposed to x-ray doses rangin g from 0 to 400 rads. Forty days after exposure the mice were killed a nd the testes and cauda epididymal sperm removed surgically. Flow cyto metric measurements of acridine orange stained testicular samples indi cated a repopulation of testicular cell types following x-ray killing of stem cells. Cauda epididymal sperm were analyzed by the sperm chrom atin structure assay (SCSA), a flow cytometric measurement of the susc eptibility of the sperm nuclear DNA to in situ acid denaturation. The SCSA detected increased susceptibility to DNA denaturation in situ aft er 12.5 rads of x-ray exposure, with significant increases following 2 5 rads. Abnormal sperm head morphology was not significantly increased until the testes were exposed to 60 rads of x-rays. These data sugges t that the SCSA is currently the most sensitive, noninvasive method of detecting x-ray damage to testicular stem spermatogonia. (C) 1995 Wil ey-Liss, Inc.