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Can bovine in vitro-matured oocytes selectively process X- or Y-sorted sperm differentially?
P Bermejo-Alvarez1, D Rizos, D Rath
1Departamento de Reproducción Animal y Conservación de Recursos Zoogenéticos, INIA, 28040 Madrid, Spain.
Biology of Reproduction
|June 27, 2008
Summary
Oocytes do not select sperm by sex. Lower fertility with sex-sorted sperm is likely due to damage during the sorting process, not female choice.
Area of Science:
- Reproductive Biology
- Animal Science
- Genetics
Background:
- Mammalian females may influence offspring sex, potentially explaining reduced fertility with sex-sorted sperm.
- In vitro fertilization (IVF) and sperm sorting technologies are advancing reproductive efficiency.
Purpose of the Study:
- To determine if in vitro matured oocytes can select X- or Y-bearing spermatozoa during fertilization.
- To investigate the impact of sperm sorting on fertilization and early embryo development.
Main Methods:
- In vitro fertilization of 1788 oocytes using X-sorted, Y-sorted, mixed, and unsorted semen.
- Assessment of cleavage rates at 48 hours post-insemination and blastocyst development until Day 9.
- Sex determination of embryos at the two- to four-cell and blastocyst stages.
Main Results:
- Cleavage rates were significantly lower in all sorted semen groups compared to unsorted semen.
- Blastocyst yields were significantly higher in the unsorted semen group.
- No significant difference in sex ratio was observed between sorted and unsorted sperm groups at any stage.
Conclusions:
- Oocytes do not exhibit preferential selection of X- or Y-bearing spermatozoa.
- Reduced fertility and developmental rates with sex-sorted sperm are attributed to damage incurred during the sorting procedure.
