Objective      To investigate the role of fibrous sheath CABYR-binding (FSCB) protein in the sperm motility and fertility in fscb gene knockout male mice.       Methods      In fscb-gene knockout mice the expression of FSCB protein in testicular tissue and sperm was observed by immunohistochemistry. In vitro the sperm motility

viability and corresponding parameters were analyzed by computer-aided sperm analysis (CASA). In vitro the fertilization ability of sperm from Fscb-gene knock out mice was studied. Male mice of homozygous Fscb-gene knock out(KO)

heterozygote(Het) and wild type(WT) were mated with C57BL/6J adult female WT mice. The pregnancy rate

and numbers of the embryos and natural born offspring were counted. Morphological changes of the gonads were also observed in filial generation of male mice.       Results      The immune fluorescence images detected no expression of FSCB protein in the testicular tissue and sperm of KO mice. The expression of FSCB protein in the testicular tissue and sperm of Het mice was significantly lower than that in WT mice. The amount and motility of sperm and the related motility parameters were not statistically different among the groups (P0.05).Furthermore

the data of in vitro fertilization (IVF)experiment showed that the sperm fertility in KO

Het and WT groups was not widely divergent from each other. The average number of sperms binding to eggs with intact zona pellucida and zona-free eggs

the fertilization rate of eggs and the pregnancy rate of the female mice was not significantly different (P0.05). Specifically

the number of embryos for each female in WT

Het and KO groups were 7.00±1.41

7.33±1.53

and 7.20±1.48

accordingly

the number of natural born offsprings was 6.00±2.00

6.75±1.71

and 7.80±1.30. In addition

the gonado genesisin filial generation of adult male mice had no obvious difference.       Conclusion      Fscb gene knockout does not affect the ability of sperm motility and fertilization in vitro and in vivo

suggestingthat the function of the FSCB protein may be unnecessary or replaceable for the maintenance of sperm motility and fertilization.