The sperm of (C57BL X C3H)Fj mice were examined 1, 4, and 10 weeks after a subacute treatment with one of 25 chemicals at two or more dose levels. The fraction of sperm that were abnormal in shape was elevated above control values of 1.2-3.4% for methyl methanesulfonate, ethyl methanesulfonate, griseofulvin, benzo[alpyrene, ME-TEPA [tris(2-methyl-1-aziridinyl)phosphine oxide], THIO-TEPA [tris(l-aziridinyl) Fig. 1A. Abnormal sperm had forms readily recognizable as different as shown in Fig. IB-F. RESULTSThe compounds chosen for study are shown in Table 1 together with their sources and a summary of their activities as mutagens, teratogens, and carcinogens in mammals treated in vivo. Each of the compounds was given to the mice by a subacute schedule (5 consecutive, daily intraperitoneal injections) at daily dosages shown in Fig. 2, delivered in 0.5 ml of appropriate vehicle, prepared fresh daily. Distilled water was used as the vehicle from all chemicals except benzo-[a]pyrene, dichlorvos, DDT [1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane], 3-methylcholanthrene, and myleran which were delivered in tricaprylin (Nutritional Biochemical Corp., Cleveland, Ohio) (4, 9). Measurements of sperm abnormalities were made at 1, 4, and 10 weeks following the end of the exposure. Sperm observed at these times were presumably exposed to the chemicals while they were spermatids, early primary spermatocytes, and spermatogonia respectively. The results of these experiments are shown in Fig. 2. It is convenient to consider first the frequency of abnormalities in all groups of control animals. A total of 29 measurements (of 2000 sperm each) were made on sperm of (C57BL X C3H/Anf)Fl and (C57BL/6 X C3H/He)Fl mice which had received either water or tricaprylin as vehicle. There was no significant difference in frequency of abnormalities in the four groups. For this reason we pooled the results from all control groups and plotted the resultant cumulative frequency distribution in Fig. 3. The mean frequency of abnormalities was 1.8% with the 90% interval for the population extending from 1.2 to 3.4%. The expected Poisson distribution for an abnormality frequency of 1.8% is shown by the solid curve. Since there is more dispersion in the counts than can be. accounted for by counting statistics
