Abstract: Adult male rats were treated orally with monomer T4 (Tripchlorolide) isolated from Tripterygium wilfordii, at the dose of 50 μg/kg/day, 6 days/week for 6 weeks.Ultrathin section and freeze etching replica of seminiferous tubules and epididymal spermatozoa were examined with elec-tron microscope. The results showed that the spemiogenesis was inhibited T4 in seminiferous tu-bules. However, the damage and disruption of the spermatozoa were more serious in the epididymis.Damage of the structure and function ot microtubule and microfilament may be the chief reason for sperm damage. Sperm membrane was also very sensitive to the treatiment of monomer T4.

Key words: Tripterygium wilfordii, Tripchlorolide (T4), Rat, Spermatozoa, Ultrastructure, Freeze-etching