Substitution of thymidine with 5-Brome-deoxyuridine (BrdU) was performed in vivo in mice for the detection of clomiphene citrate effects on SCE in sperniatogonia. Twenty four adult male mice were divided into 8 groups. One group served as control and the other groups were given clomiphena for 5 days in doses 10

25

50

75

100 times that of clinical dose (25 mg per day) respectively. Then

all animals were injected intraperitoneally 0.5 ml of suspension of BrdU adsorbed with active carbon and were killed 54 hours later after infcraperitoneal injection of colchicine (4mg/kg). Chromosome samples of spermatogonia were prepared routinely from the testis. The results of examination indicated that difference between administration groups and control group was not statistically significant (P>0.05). SCE of germ cells thus provided the evidence that clomiphene is not a mutagen