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Updated: May 17, 2026
06:53
Vitrification of In Vitro Matured Oocytes Collected from Adult and Prepubertal Ovaries in Sheep
Published on: July 10, 2021
Regulation of sheep oocyte maturation using cAMP modulators
Ryan D Rose1, Robert B Gilchrist, Jennifer M Kelly
1The Robinson Institute, Research Centre for Reproductive Health, School of Paediatrics and Reproductive Health, The University of Adelaide, Adelaide, South Australia, Australia.
Theriogenology
|October 30, 2012
Summary
Modulating cyclic adenosine monophosphate (cAMP) levels in ovine oocytes during in vitro maturation (IVM) delays nuclear maturation. This approach enhances embryo quality by increasing blastocyst cell number, improving developmental competence.
Area of Science:
- Reproductive Biology
- Developmental Biology
- Cellular Signaling
Background:
- Oocyte maturation is critical for successful reproduction.
- Spontaneous meiosis resumption upon removal from follicles decreases oocyte developmental competence due to altered cyclic adenosine monophosphate (cAMP) levels.
- Asynchronous cytoplasmic and nuclear maturation negatively impacts embryo development.
Purpose of the Study:
- To investigate the effect of modulating cyclic adenosine monophosphate (cAMP) concentrations in ovine cumulus-oocyte complexes (COCs) during in vitro maturation (IVM).
- To delay spontaneous nuclear maturation and enhance oocyte developmental competence.
- To improve embryo quality in sheep.
Main Methods:
- Abattoir-derived ovine COCs were pre-cultured with forskolin (FSK) and 3-isobutyl-1-methylxanthine (IBMX) to elevate cAMP levels.
- COCs underwent in vitro maturation (IVM) with FSH and cilostamide.
- Nuclear maturation progression and embryo development rates were assessed.
- Blastocyst cell number was quantified.
Main Results:
- Pre-IVM treatment with FSK and IBMX significantly increased ovine COC cAMP concentrations (10-fold).
- Elevated cAMP delayed, but did not inhibit, the completion of nuclear maturation (metaphase II) by 3-4 hours compared to standard IVM.
- No significant difference in embryo development rates was observed.
- A significant increase in blastocyst total cell number was noted (103 ± 6 vs. 66 ± 4 cells) in the modulated cAMP group compared to standard IVM.
Conclusions:
- Regulation of ovine oocyte cAMP concentrations during IVM effectively delays nuclear maturation.
- This modulation improves embryo quality, specifically by increasing the total cell number of blastocysts.
- The findings suggest a potential strategy to enhance developmental competence in mammalian oocytes.
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