Optimal ICSI timing after the first polar body extrusion in in vitro matured human oocytes.
BACKGROUND
This study was conducted to investigate the fertilization and embryo development of human oocytes injected at different time intervals after extrusion of the first polar body (PB) following in vitro maturation (IVM) in IVM cycles. Also, we evaluated whether spindle imaging could serve as a tool to determine the optimal ICSI time.


METHODS
Oocytes were collected from 43 women with polycystic ovary syndrome. Metaphase I (MI) oocytes after in vitro culture for 24 h from germinal vesicle stage were subjected to ICSI according to time after first PB extrusion. The intervals were: within 1 h (n=38); 1-2 h (n=30); 2-4 h (n=26);4-6 (n=28) and 6-8 h (n=40). In some MI oocytes, viable spindle location was evaluated using Polscope microscopy at different time intervals after first PB extrusion.


RESULTS
Fertilization rate of the MI oocytes injected within 1 h after first PB extrusion was low (15.8; 6/38) (P<0.01 versus all other times). In contrast, the fertilization rate was 80, 92.3, 82.1 and 85% for oocytes injected 1-2, 2-4, 4-6 and 6-8 h after first PB extrusion, respectively. Development of good-quality embryos was not significantly different among all the groups. Interestingly, all the oocytes injected within 1 h after first PB extrusion were in Telophase I.


CONCLUSIONS
Human oocytes matured in vitro needed at least 1 h after first PB extrusion to complete nuclear maturation. Use of a live spindle imaging system can help to decide the timing of ICSI for oocytes matured in vitro.
Hyun
Chang-Seop
CS
Maria Infertility Hospital, Seoul, Republic of Korea.
Cha
Jung-Ho
JH
Son
Weon-Young
WY
Yoon
San-Hyun
SH
Kim
Kyung-Ae
KA
Lim
Jin-Ho
JH
D000328:Adult; D002970:Cleavage Stage, Ovum; D046149:Embryo Culture Techniques; D004624:Embryo Transfer; D047108:Embryonic Development; D005260:Female; D005306:Fertilization; D005307:Fertilization in Vitro / Q000379:methods*; D006801:Humans; D009865:Oocytes / Q000378:metabolism*; D011085:Polycystic Ovary Syndrome / Q000378:metabolism* / Q000628:therapy; D011247:Pregnancy; D011256:Pregnancy Outcome; D020554:Sperm Injections, Intracytoplasmic / Q000379:methods*; D008941:Spindle Apparatus / Q000378:metabolism