Vitrification of in vitro matured oocytes: effects on meiotic spindle configuration and mitochondrial function.
BACKGROUND
In the assisted reproductive technique, cryopreserving in vitro-matured oocytes is a new strategy to extend the pool of total oocytes. However, oocyte cryopreservation technique is still unsatisfied. So the assessment of cyro-damage on meiotic spindle and mitochondrial function is necessary to evaluate and refine the current protocols.


METHODS
The immature oocytes were donated from women undergoing ICSI cycles. Cytoskeleton was assessed by α-tubulin and mitochondria through the fluorescent ΔΨm reporter JC-1.


RESULTS
Relative inner membrane potential in MII oocytes from vIVM group sharply decreased, compared with the control (n=30) (1.397 vs. 1.019, P<0.05). 45.2% defective spindles were observed in fIVM group, compared with 48.0% in vIVM group (P>0.05). Oocytes in fIVM (35.5%, 11/31) and vIVM (40.0%, 10/25) displayed abnormal chromosome (P>0.05).


CONCLUSIONS
In vitro maturation (IVM) has an adverse effect on the organization of spindle and chromosome, and no significantly effect on spindle and chromosome was discovered after vitrification-thaw cycle, while there was obvious damage of oocyte mitochondrial function of in vitro-matured oocyte detected after warming, which may be the reason of the low following developmental potential.
Department of Reproductive Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology Wuhan, China.
Tao
T
Lei
Department of Reproductive Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology Wuhan, China.
Na
N
Guo
Department of Anesthesiology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology Wuhan, China.
Jie-Qiong
JQ
Liu
Department of Reproductive Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology Wuhan, China.
Mei-Hua
MH
Tan
Department of Reproductive Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology Wuhan, China.
Yu-Feng
YF
Li
D000328:Adult; D015925:Cryopreservation / Q000379:methods*; D005260:Female; D006801:Humans; D059471:In Vitro Oocyte Maturation Techniques / Q000379:methods*; D008928:Mitochondria / Q000473:pathology*; D009865:Oocytes / Q000473:pathology*; D008941:Spindle Apparatus / Q000473:pathology*; D058989:Vitrification; D055815:Young Adult
Assisted reproduction; human oocytes; mitochondrial function; spindle; vitrification