Effects of sperm viability on fertilization and embryo cleavage following intracytoplasmic sperm injection.
OBJECTIVE
In the human, intracytoplasmic sperm injection is typically performed using "viable" sperm which has been mechanically rendered nonmotile. The purpose of the present study was to determine the ability of nonviable sperm to fertilize human oocytes and the early developmental normalcy of the resulting embryos.


METHODS
In this study, immature, prophase I oocytes from a total of 27 consenting patients were matured in vitro and then randomized into two groups: injection with a viable human sperm or injection with a sperm rendered nonviable by freeze-thawing in liquid nitrogen. The rates of fertilization and cleavage were compared between the two groups.


RESULTS
The results demonstrated a significantly higher two-pronuclear fertilization rate when oocytes were injected with viable sperm (62.2%) compared to when oocytes were injected with nonviable sperm (16.2%). Oocytes injected with viable sperm also demonstrated a higher cleavage rate (91 vs 33%).


CONCLUSIONS
These findings suggest that while the intracytoplasmic injection of nonviable human sperm can result in normal fertilization, it does so at a much reduced rate compared to viable sperm and may not result in normally cleaving embryos.
Poe-Zeigler
R
R
Jones Institute for Reproductive Medicine, Department of Obstetrics and Gynecology, Eastern Virginia Medical School, Norfolk 23507, USA.
Nehchiri
F
F
Hamacher
P
P
Boyd
C
C
Oehninger
S
S
Muasher
S
S
Lanzendorf
S E
SE
D002470:Cell Survival; D005314:Embryonic and Fetal Development; D005307:Fertilization in Vitro / Q000379:methods*; D006801:Humans; D008297:Male; D008845:Microinjections; D009865:Oocytes; D013094:Spermatozoa / Q000166:cytology*; D015053:Zygote / Q000254:growth & development