Marked improvement of fertility of cryopreserved C57BL/6J mouse sperm by depletion of Ca2+ in medium
2009
Suzuki Migishima, R.(Mitsubishi Kagaku Inst. of Life Sciences, Tokyo (Japan)) | Hino, T. | Takebe, M. | Oda, K. | Migishima, F. | Morimoto, Y. | Yokoyama, M.
Cryopreservation of mouse sperm is useful for maintaining various strains. However, fertility generally decreases after freezing. In particular, the fertility of cryopreserved C57BL/6J sperm is very low. To improve the fertility of frozen sperm, we examined the efficiencies of various media used for sperm preincubation (SP) and in vitro fertilization (IVF) in frozen C57BL/6J sperm. In this study, SP medium was examined for efficiency of fertility with respect to content, especially calcium (Casup(2+)), phosphate (PO4sup(3-)) and lactate. In all media containing no Casup(2+), including medium lacking Casup(2+), lacking Casup(2+) and PO4sup(3-), lacking Casup(2+) and lactate and lacking Casup(2+), PO4sup(3-) and lactate, high IVF rates were obtained (79, 69, 76 and 71%, respectively). On the other hand, the rates for media containing Casup(2+) were significantly lower (30-38%, P0.05). After transfer, 41-50% of newborns were obtained in all media containing no Casup(2+). In conclusion, preincubation of thawed sperm in medium containing no Casup(2+) markedly improved the fertility of cryopreserved C57BL/6J sperm. These results indicate that the present method of IVF using medium with no Casup(2+) is practical for use in cryopreserved C57BL/6J sperm.
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