Presence of cumulus cells during in vitro fertilization protects the bovine oocyte against oxidative stress and improves first cleavage but does not affect further development

The present study was conducted to evaluate the function of cumulus cells during bovine IVF Oocytes within cumulus-oocyte complexes (COCs) or denuded oocytes (DOs) were inseminated in control medium, or DOs were inseminated in cumulus cell conditioned medium (CCCM). DOs exhibited reduced cleavage an...

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Bibliographic Details
Published in:	Zygote (Cambridge) Vol. 13; no. 2; p. 177
Main Authors:	Fatehi, A Nader, Roelen, Bernard A J, Colenbrander, Ben, Schoevers, Eric J, Gadella, Bart M, Beverst, Mart M, van den Hurk, Rob
Format:	Journal Article
Language:	English
Published:	England 01-05-2005
Subjects:	Animals Cattle Culture Media, Conditioned Embryonic Development - drug effects Embryonic Development - physiology Female Fertilization in Vitro - veterinary Hydrogen Peroxide - toxicity In Situ Nick-End Labeling - veterinary Microscopy, Fluorescence, Multiphoton - veterinary Oocytes - drug effects Oocytes - physiology Ovarian Follicle - cytology Oxidative Stress - physiology
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Summary:	The present study was conducted to evaluate the function of cumulus cells during bovine IVF Oocytes within cumulus-oocyte complexes (COCs) or denuded oocytes (DOs) were inseminated in control medium, or DOs were inseminated in cumulus cell conditioned medium (CCCM). DOs exhibited reduced cleavage and blastocyst formation rates when compared with intact COCs. The reduced blastocyst formation rate of DOs resulted from reduced first cleavage but subsequent embryo development was not changed. Live-dead staining and staining for apoptotic cells revealed no differences in blastocysts from oocytes fertilized as COC or DO. Fertilization of DOs in CCCM partially restored the cleavage rate, suggesting that factors secreted by cumulus cells are important for fertilization but that physical contact between oocytes and cumulus cells is required for optimal fertilization and first cleavage. Exposure of COCs to hydrogen peroxide shortly before fertilization reduced the cleavage rate, but did not lead to enhanced death of cumulus cells or oocyte death. Exposure of DOs to hydrogen peroxide, however, resulted in oocyte death and a complete block of first cleavage, suggesting that cumulus cells protect the oocyte against oxidative stress during fertilization.
ISSN:	0967-1994
DOI:	10.1017/S0967199405003126