[Mammalian spermatogenesis as a biological indicator for ionizing radiation].

We have analysed spermatogenetic cells by flow cytometry to quantify effects of ionizing radiation. The radiation-induced reductions of testicular DNA-synthesizing cells, primary spermatocytes, haploid round and elongated spermatids as well as the increases of numerical chromosome aberrations (abnormal diploid spermatids and aneuploidies) in NMRI inbred mice are described. Testicular weights were determined as a parameter of germ cell decrease, and histologic cross sections of the testes were analysed. Since even an exposure of 0.05 Gy (= 5 rad) may be detected by a reduction of DNA-synthesizing cells (Acta Radiol. Oncol. Radiat. Phys. Biol. 21, 349-351 (1982) [1]), the use of the in vivo system "spermatogenesis" as a biological dosimeter to monitor low dose effects and to determine RBE values of different radiation qualities is suggested.