Paper Information

Journal:   INTERNATIONAL JOURNAL OF FERTILITY AND STERILITY   SUMMER 2011 , Volume 5 , Number SUPPLEMENT 1; Page(s) 48 To 48.
 
Paper:  EMBRYOLOGY: TIME DEPENDENT EFFECT OF POST WARMING INTERVAL ON MICROTUBULE ORGANIZATION, MEIOTIC STATUS, AND PARTHENOGENETIC ACTIVATION OF VITRIFIED IN VITRO MATURED SHEEP OOCYTES
 
Author(s):  ASGARI V.*, HOSSEINI S.M., OSTADHOSSEINI S., HAJIAN M., NASR ESFAHANI M.H.
 
* DEPARTMENT OF REPRODUCTION AND DEVELOPMENT, REPRODUCTIVE BIOMEDICINE CENTER, ROYAN INSTITUTE FOR ANIMAL BIOTECHNOLOGY, A.C.E.C.R., ISFAHAN, IRAN
 
Abstract: 

Background: It is a common practice to rest vitrified-warmed matured oocytes for 1-3 hours, as a treatment to recover spindle and cytoskeleton, before commencing a further treatment. Vitrified-warmed matured oocytes, however, are very sensitive and may resume meiosis spontaneously during this recommended rest time. Therefore, the aim of this study was to assess spindle and chromosome status as well as developmental competence of vitrified in vitro matured parthenogenetically activated sheep oocytes.
Materials and Methods: Vitrified-warmed oocytes along with their corresponding non-vitrified oocytes activated parthenogenetically, either 0 hour (immediately) or 2 hours (delayed) after warming.
Results: There was no significant effect of post-warming interval on the proportion of degenerated oocytes. Evaluation of chromosomes and meiotic spindle configuration showed that 11.11% of oocytes in the immediate group and 8.82% of oocytes in the delayed group had normal chromosomal alignment on well-structured spindles, compared to non-vitrified group (79.41%). Meanwhile, majority of the chromosomal abnormalities in the immediate and delayed groups were categorized as absent (unobservable) (77.78%) and anapest II (70.59%), respectively. Oocytes in immediately activated group showed significantly higher blastocyst rate (28.86%) compared to delayed activated group (16.47%).
Conclusion: The results suggest that post-warming interval may have important consequence on meiotic progression and parthenogenetic activation of vitrified oocytes. In sheep, it appears that chemical activation without having to await microtubule reorganization improves embryonic development.

 
Keyword(s): CRYOPRESERVATION, OOCYTE, MEIOSIS RESUMPTION, DEVELOPMENTAL COMPETENCE
 
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