Fertilization and embryo development in a mouse ICSI model using human and mouse sperm after immobilization in polyvinylpyrrolidone.
BACKGROUND
For human ICSI, sperm are normally immobilized immediately prior to injection. However, there are some situations when only sperm of questionable viability are available. There are few evaluations of fertilization or developmental problems in human or animal models using sperm having known intervals between immobilization and injection.


METHODS
Immobilized human sperm were maintained for 1-24 h in 10% polyvinylpyrrolidone (PVP) before injection into mouse oocytes. Mouse sperm heads were similarly maintained in either PVP or a high potassium-containing 'nucleus isolation medium' (NIM) before ICSI and embryo development to the blastocyst stage.


RESULTS
Immobilized human sperm activated mouse oocytes comparably to controls even 24 h after immobilization. However, mouse sperm heads showed a decrease in activating ability 6 h after isolation, either in PVP or NIM. A significant reduction in blastocyst development occurred if mouse sperm heads were maintained for even 1 h in PVP. After 6 h, no blastocysts formed, with arrest occurring at the morula stage. NIM provided partial protection for up to 3 h.


CONCLUSIONS
Immobilized human sperm maintained oocyte activating activity for 24 h. However, mouse sperm are susceptible to alterations that affect both fertilization and development.
Kapiolani Medical Center, Department of Obstetrics and Gynecology, University of Hawaii School of Medicine, Honolulu, HI 96826, USA. kmizuno@res.yamanashi-med.ac.jp
Kaoruko
K
Mizuno
Kazuhiko
K
Hoshi
Thomas
T
Huang
D000818:Animals; D001755:Blastocyst / Q000502:physiology; D004622:Embryo, Mammalian / Q000502:physiology*; D005314:Embryonic and Fetal Development; D005260:Female; D005306:Fertilization; D006801:Humans; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D011205:Povidone / Q000494:pharmacology*; D013077:Sperm Head / Q000187:drug effects / Q000502:physiology; D020554:Sperm Injections, Intracytoplasmic; D013081:Sperm Motility / Q000187:drug effects*; D013084:Sperm-Ovum Interactions; D013094:Spermatozoa / Q000187:drug effects* / Q000502:physiology*; D013997:Time Factors
D011205:Povidone