Meiotic spindle recovery is faster in vitrification of human oocytes compared to slow freezing.
OBJECTIVE
To investigate spindle behavior during and after slow freezing at room temperature (RT) and vitrification at different temperatures.


METHODS
Randomized, comparative study.


METHODS
University hospital.


METHODS
Patients undergoing IVF treatment volunteered for the study and donated part of their supernumerary oocytes.


METHODS
Metaphase II oocytes were divided into group A: slow freezing RT /thawing RT; group B: vitrification RT/warming RT; group C: vitrification RT/warming 37 degrees C; and group D: vitrification 37 degrees C/warming 37 degrees C. Spindle presence was evaluated at each step of the four procedures and in culture.


METHODS
Cumulative spindle recovery rate comparing warming phase of the three vitrification groups and culture phase among the four groups.


RESULTS
During warming, the three vitrification groups showed a significantly fast spindle recovery rate compared to the thawing of the slow freezing group. A progressively significant fast cumulative recovery rate was observed in the three vitrification groups by increasing the number of phases at physiological temperature (hazard rate = 2.68; 95% confidence interval 1.71-4.02).


CONCLUSIONS
The present study demonstrates that spindle recovery is faster in vitrification than in slow freezing. These data support a possible protective effect of vitrification/warming at 37 degrees C on the meiotic spindle structure and, therefore, on the subsequent clinical outcome of the procedure, although comparative clinical studies are needed.
Ciotti
Patrizia Maria
PM
Reproductive Medicine Unit, IVF and Infertility Centre, S.Orsola-Malpighi University Hospital, University of Bologna, Bologna, Italy. patriziamaria.ciotti@aosp.bo.it
Porcu
Eleonora
E
Notarangelo
Leonardo
L
Magrini
Otello
O
Bazzocchi
Antonia
A
Venturoli
Stefano
S
D018929:Cell Culture Techniques / Q000379:methods; D003599:Cytoskeleton / Q000502:physiology / Q000648:ultrastructure; D005260:Female; D005307:Fertilization in Vitro / Q000379:methods; D005615:Freezing; D006801:Humans; D008540:Meiosis / Q000502:physiology*; D054315:Oocyte Retrieval / Q000379:methods; D009865:Oocytes / Q000166:cytology* / Q000502:physiology*; D011897:Random Allocation; D013696:Temperature; D014021:Tissue Preservation / Q000379:methods