@article{oai:repo.qst.go.jp:00045248,
 author = {Kito, Seiji and Oota, Yuki and 鬼頭 靖司 and 太田 有紀},
 issue = {3},
 journal = {Zygote},
 month = {Jun},
 note = {To optimize IVF conditions for BALB/c mice, known to have poor in vitro fertilizability, requirements for sperm-ova interaction were studied by use of modified simplex optimization medium (mKSOM) as a basic medium.  Modified human tubal fluid (mHTF) was used for sperm preincubation and acted as a positive control.  When the two media were compared, neither capacitation nor fertilization was supported in mKSOM.  Increasing calcium in mKSOM to 5 mM or more during sperm:ova coincubation improved zona penetration but not male pronuclear (MPN) formation to the same level as those in mHTF.  When medium osmolarity was varied from 230-305 mOsmols by NaCl at 5 mM CaCl2, MPN formation improved at 280 mOsmols or higher osmolarity to the same level as that in mHTF.  When NaCl equivalent to 25-75 mOsmols was substituted with trehalose, no significant reduction in fertilization was observed.  Substitution of NaCl equivalent to 75 mOsmols with other osmotic reagents (sucrose, choline chloride and sorbitol) resulted in similar levels of fertilization with mHTF except for sorbitol, which significantly reduced fertilization due to its detrimental effect on sperm viability.  At isotonic osmolarity (305 mOsmols), maximum fertilization was observed at 5 mM CaCl2; lower or higher concentrations resulted in reduced fertilization.  Thus, calcium and osmolarity are important for sperm:ova interaction in BALB/c mice, and increasing calcium to 5 mM and osmolarity to 305 mOsmols is optimal for BALB/c sperm to penetrate through the zona and to form MPN.},
 pages = {249--257},
 title = {In vitro fertilization in inbred BALB/c mice I: isotonic osmolarity and increased calcium-enhanced sperm penetration through the zona pellucida and male pronuclear formation},
 volume = {16},
 year = {2008}
}