title: Improvement in the development of oocytes from C57BL/6 mice after sperm injection.
abstract: The C57BL/6 mouse strain is used widely for producing transgenic and knockout strains. Sperm motility is extremely low after a freeze-thaw process. Although intracytoplasmic sperm injection (ICSI) can be used to produce embryos from sperm with low or even no motility, its success rate is poor in the C57BL/6 strain. In particular, the survival of C57BL/6 oocytes after ICSI is extremely low compared with that of hybrid strains. We found that the survival percentages of C57BL/6J oocytes (63% and 64%) were lower than those of B6D2F1 oocytes (80% and 80%) when B6D2F1 and C57BL/6J sperm were injected, respectively. For C57BL/6J mice, 87%, 72%, 64%, 56%, and 59% of oocytes survived after ICSI in media containing 61.62, 71.62, 81.62, 91.62, and 101.62 mM NaCl, respectively. In addition, 64%, 81%, and 79% of oocytes survived after ICSI in media with 4.83, 14.83, and 24.83 mM KCl, respectively. Our results suggest that the survival of C57BL/6J oocytes after ICSI is improved by using Na(+)-deficient and K(+)-rich media.
authors.affiliation: Division of Reproductive Engineering, Center for Animal Resources and Development, Kumamoto University, Kumamoto, Japan. tkaneko@anim.med.kyoto-u.ac.jp
authors.forename: Takehito
authors.initials: T
authors.lastname: Kaneko
authors.forename: Reiichiro
authors.initials: R
authors.lastname: Ohno
mesh_terms: D000818:Animals; D003470:Culture Media; D046149:Embryo Culture Techniques; D005260:Female; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL / Q000196:embryology*; D009865:Oocytes / Q000254:growth & development*; D020554:Sperm Injections, Intracytoplasmic / Q000662:veterinary*
chemical_list: D003470:Culture Media