[Cryopreservation by cryoloop damages human immature oocytes].
OBJECTIVE
To examine the influence of cryoloop on the spindle and chromosome configurations of human oocytes cryopreserved in the germinal vesicle (GV) and metaphase II (M II) stages, as well as on the survival rate and potential for in vitro maturation (IVM).


METHODS
GV oocytes were randomly assigned into a control group (matured in vitro into the M II stage), a GV cryopreserved group (cryopreserved in the GV stage and then matured in vitro), and an M II cryopreserved group (matured in vitro and cryopreserved in the M II stage). After cryopreservation and IVM, immunostaining of the tubulin and chromatin was performed followed by visualization using laser scanning confocal microscopy (LSCM).


RESULTS
A significantly higher survival rate was observed in the GV cryopreserved group than in the M II , but the maturation rate showed no significant difference between the GV cryopreserved group and the control (P > 0.05). Compared with the control group, there was a statistically significant decrease in the rates of normal meiotic spindles and chromosomes in the GV cryopreserved group (P < 0.05). A significantly lower rate of normal spindles was noted in the M II cryopreserved group than in the control, but no statistical difference was shown in the rate of normal meiotic chromosomes between the two groups (P > 0.05).


CONCLUSIONS
Cryopreservation by cryoloop has a damaging effect on the spindle and chromosome of human oocytes in the GV and M II stages.
Li
Yu-feng
YF
Reproductive Center, Department of Gynecology and Obstetrics, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China. yufengli64@yahoo.com.cn
He
Qiao-hua
QH
Zhang
Han-wang
HW
Zhu
Gui-jin
GJ
Hu
Juan
J
Liu
Qun
Q
Ren
Xin-ling
XL
Wei
Yu-lan
YL
D002470:Cell Survival; D002478:Cells, Cultured; D002843:Chromatin / Q000378:metabolism; D015925:Cryopreservation / Q000379:methods*; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008677:Metaphase; D018613:Microscopy, Confocal; D009865:Oocytes / Q000166:cytology* / Q000254:growth & development / Q000378:metabolism; D010062:Ovulation Induction / Q000379:methods*; D013997:Time Factors; D014404:Tubulin / Q000378:metabolism
D002843:Chromatin; D014404:Tubulin