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. 2010 May;27(5):239-46.
doi: 10.1007/s10815-010-9401-z. Epub 2010 Mar 9.

In vitro maturation, apoptotic gene expression and incidence of numerical chromosomal abnormalities following cryotop vitrification of sheep cumulus-oocyte complexes

Bita Ebrahimi  1 , Mojtaba Rezazadeh Valojerdi, Poopak Eftekhari-Yazdi, Hossein Baharvand
Affiliations

In vitro maturation, apoptotic gene expression and incidence of numerical chromosomal abnormalities following cryotop vitrification of sheep cumulus-oocyte complexes

Bita Ebrahimi et al. J Assist Reprod Genet. 2010 May.

Abstract

Purpose: The purpose of this study was to evaluate the effects of cryotop vitrification of sheep cumulus-oocyte complexes (COCs) on oocyte maturation, apoptotic gene expression and incidence of chromosomal abnormalities.

Methods: Freshly isolated (control group) and vitrified-warmed COCs (cryotop group) were matured in vitro. The expression of pro- and anti-apoptotic genes was investigated by real-time PCR. The incidence of numerical chromosomal abnormalities was evaluated by cytogenetic analysis.

Results: The mean percentage of oocytes in the cryotop and control groups that reached metaphase II was 49.25 +/- 3.01% and 51.94 +/- 2.7% respectively. The expression rates of pro- and anti-apoptotic genes were similar in both groups, whereas the incidence of numerical chromosomal abnormalities was higher in the cryotop group compared to the control group (42.5% vs. 20%, p < 0.05).

Conclusion: Although cryotop vitrification of COCs did not affect the incidence of oocyte maturation or apoptotic gene expression, significant deficiencies in the maintenance of oocyte chromosomal organization were seen.

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Figures

Fig. 1
Fig. 1
(A) Healthy oocytes before and after in vitro maturation, (B) Different nuclear stages of oocytes in the control and cryotop groups. Note: Same superscripts show significant difference. a (p value ≤ 0.0001); b (p value = 0.003)
Fig. 2
Fig. 2
Fold differences of expression of relative apoptotic genes in the cryotop and control groups. Note: Data is shown as mean±SEM
Fig. 3
Fig. 3
Normal and abnormal chromosome number in mature oocytes. (A&B) control group, (C&D) cryotop group. Original magnification: 1000×
See this image and copyright information in PMC

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