Cryoloop vitrification of rabbit oocytes.
BACKGROUND
Vitrification is assumed to be a promising method to cryopreserve human oocytes but still needs optimization. In this study, rabbit oocytes (fertilized by ICSI) were vitrified with cryoloops, and the effect of three different cryopreservation protocols on spindle configuration and embryo quality was assessed.


METHODS
Metaphase II rabbit oocytes were randomly assigned to one of four groups: (i) control; (ii) E40 [40% ethylene glycol (EG)]; (iii) ED20 [20% EG + 20% dimethylsulphoxide (DMSO)]; and (iv) ED20 + M (20% EG + 20% DMSO + vitrification machine). After warming, one part of each group was fertilized by ICSI to examine the fertilization and embryo cleavage ability, and the others were immunostained for tubulin and chromatin before visualization using confocal microscopy.


RESULTS
The survival rates after warming were 79.1, 83.1 and 82.3%, respectively. In protocols E40 and ED20, the spindles were severely injured and the embryo quality not good compared with those in the ED20 + M group.


CONCLUSIONS
The fastest cooling rate in combination with EG and DMSO as cryoprotectants had the fewest adverse effects on the spindle configuration of rabbit oocytes and embryo development.
Cai
X Y
XY
Department of Obstetrics and Gynaecology, Third Hospital, Peking University, Peking, China 100083.
Chen
G A
GA
Lian
Y
Y
Zheng
X Y
XY
Peng
H M
HM
D000818:Animals; D002875:Chromosomes / Q000648:ultrastructure; D015925:Cryopreservation / Q000379:methods*; D003451:Cryoprotective Agents; D004121:Dimethyl Sulfoxide; D047108:Embryonic Development; D019855:Ethylene Glycol; D005260:Female; D006801:Humans; D066298:In Vitro Techniques; D008677:Metaphase; D008870:Microtubules / Q000648:ultrastructure; D009865:Oocytes / Q000166:cytology; D011817:Rabbits; D020554:Sperm Injections, Intracytoplasmic; D008941:Spindle Apparatus / Q000648:ultrastructure
D003451:Cryoprotective Agents; D019855:Ethylene Glycol; D004121:Dimethyl Sulfoxide