PARENT SESSION

(M328) RELATIONSHIPS BETWEEN SPERM MORPHOLOGY AND IN VITRO FERTILIZATION ABILITY IN MICE.

Kawai, Yasuhiro¹, Hata, Tomoko¹, Suzuki, Osamu¹, Matsuda, Junichiro¹, ¹ National Institute of Infectous Diseases, Tokyo, Japan

ABSTRACT- IVF is one of the reproduction techniques and widely used in reproduction researches. Some mouse strains, however, exhibit low fertilization ability in in vitro with their epididymal sperm. To clarify these strain difference in the fertilization ability in vitro, we examined the effect of morphology and constituted proteins of epididymal sperm on the in vitro fertilizability in mice. Sperm suspensions were obtained from C57BL/6J, BALB/cA, C3H/HeN, DBA/2J, 129x1/SvJ. Sperm morphology was examined with sperm fixed by 10% formalin. Spapes of sperm tails were classified into three categories: straight, positive bended tail (PBT), negative bended tail (NBT). Abnormal sperm head and hairpin at the neck was also recorded. Forms of cytoplasmic droplets (CD) was assigned to two categories: heavy CD (HCD), light CD (LCD). The fertilizability of these sperm was examined by IVF with oocytes of Slc: ICR oocytes. Of all five strains tested, the rate of hairpin at the neck in the C57BL/6J and rate of abnormal head in BALB/cA was highest. Although the rate of straight tail in DBA /2J was lowest, the rate of PBT was highest. The rate of HCD in 129x1/SvJ and C57BL/6J were higher than the other three strains, while the rate of LCD in DBA/2J, BALB/cA and C3H/HeN were higher than these two strains. The rank order of fertilization rate was 129x1/SvJ > C57BL/6J > C3H/HeN > BALB/cA > DBA/2J. These data show that fertilization rate might be inversely correlated with HCD, NBT and hairpin head rate. Two-dimensional electrophoretic analyses of sperm proteins of five strains revealed that the amount of component proteins in epididymal sperm were different among strains. In conclusion, these results suggest that differential morphology of epididymal sperm, in particular, NBT and HCD would be tightly related with low fertilizability in vitro.

KEY WORDS: sperm morphology, In vitro fertilization, inbred mice, sperm proteins