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Cumulus cell function during bovine oocyte maturation, fertilization, and embryo development in vitro
L Zhang1, S Jiang, P J Wozniak
1Department of Animal Science, Louisiana State University, Baton Rouge.
Molecular Reproduction and Development
|March 1, 1995
Summary
Removing cumulus cells before oocyte maturation severely impairs cattle embryo development. However, co-culturing with cumulus cells after fertilization improves embryo development to the morula and blastocyst stages.
Area of Science:
- Veterinary Science
- Reproductive Biology
- Embryology
Background:
- Cumulus cells are crucial for oocyte maturation and fertilization in assisted reproductive technologies.
- Their removal is necessary for micromanipulation techniques like sperm microinjection and nuclear transfer.
- Understanding the precise role of cumulus cells at different stages is vital for optimizing in vitro embryo production.
Purpose of the Study:
- To evaluate the function of cumulus cells during in vitro oocyte maturation, fertilization, and early embryo development in cattle.
- To determine the impact of cumulus cell removal at various time points on developmental rates.
- To assess the benefits of cumulus cell co-culture on embryo progression.
Main Methods:
- Cumulus cells were removed from bovine oocytes before maturation, after maturation, and at 0, 7, 20, and 48 hours post-fertilization.
- Cumulus-free oocytes/embryos were cultured alone or on cumulus cell monolayers.
- Developmental rates to cleavage, morula, and blastocyst stages were statistically analyzed using categorical data modeling (CATMOD).
Main Results:
- Removal of cumulus cells before maturation drastically reduced oocyte maturation (4-26%), fertilization (0-9%), and subsequent development.
- Removal at or shortly after in vitro fertilization (IVF) significantly decreased fertilization (58-71%), cleavage (40-54%), and morula/blastocyst development (15-24%) compared to controls (91-92% fertilization, 74-78% cleavage, 45% morula/blastocyst).
- Cumulus cell co-culture initiated post-fertilization did not affect fertilization or cleavage but significantly improved development to morula/blastocyst stages (P < 0.05).
Conclusions:
- Cumulus cells are essential for successful in vitro maturation and fertilization in cattle.
- The timing of cumulus cell removal significantly impacts embryo developmental potential.
- Co-culturing with cumulus cells can enhance later-stage embryo development in vitro.