Abstract: The effects of octadecanoic acid-3,4-furanodiyl ester on Kunming male mice sperm ultra-structural characteristics were studied in vitro.Kill 10 healthy fertile mice and collect the testicle,and,with a swim-up technique,a sperm suspension of high motility and purity was obtained.Determine the instant spermicidal action (mg·mL^-1·20 s) of octadecanoic acid-3,4-furanodiyl ester,isolated from the chloroform extract of neem oil,and the sperm pellets were fixed in 2.5% glutaraldehyde (pH was 7.2) and observed in electron microscope.Octadecanoic acid-3,4-furanodiyl ester can kill all sperm of Kunming mice in vitro in less than 20 s at the concentration of 4 g/L.On electron microscope,the acrosome and karyotheca of spermatids had been damaged.Small-to-large damaged areas which seemed to have been bitten by worms could be observed at the edge of the cytoplasmic membrane.In some cases,membrane and the peripheral mitochondria were virtually absent and the entire cytoplasm was medullary degenerated and vacuolated.The octadecanoic acid-3,4-furanodiyl ester has strong sperm-killing activity in vitro.There are evident histological changes due to octadecanoic acid-3,4-furanodiyl ester in sperm of male Kunming mice.

Key words: octadecanoic acid-3,4-furanodiyl ester, spermicidal activity, ultrastructural