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The uterine environment modulates trophectodermal POU5F1 levels in equine blastocysts.
Y H Choi1, H D Harding, D L Hartman
1Department of Veterinary Physiology and Pharmacology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, Texas 77843-4466, USA.
Reproduction (Cambridge, England)
|June 16, 2009
Summary
Equine embryo culture impairs trophectodermal POU5F1 expression, but the uterine environment restores normal POU5F1 patterns, suggesting in vitro culture artifacts influence species comparisons.
Area of Science:
- Reproductive Biology
- Developmental Biology
- Genetics
Background:
- Trophectodermal expression of POU5F1 protein in blastocysts varies across species, potentially impacting placental development.
- Horses exhibit delayed placental formation, making their embryonic POU5F1 expression patterns of particular interest.
Purpose of the Study:
- To investigate the pattern of embryonic POU5F1 expression in horses, a species with delayed placental formation.
- To determine if the uterine environment influences POU5F1 expression in equine embryos.
Main Methods:
- Immunohistochemical analysis of POU5F1 protein expression in in vitro-produced (IVP) and in vivo-produced equine embryos.
- Transfer of IVP blastocysts to recipient mares (IVP-ET) followed by embryo recovery.
- Quantitative real-time PCR (qPCR) to assess POU5F1, SOX2, and NANOG mRNA levels in blastocyst cells.
Main Results:
- In vitro culture led to decreased POU5F1 expression in equine embryos, with nuclear staining increasing by day 7.
- In vivo-produced blastocysts showed reduced trophoectodermal POU5F1 expression compared to IVP blastocysts.
- IVP-ET embryos exhibited POU5F1 expression patterns similar to in vivo-produced embryos, with higher POU5F1, SOX2, and NANOG mRNA in the inner cell mass than trophectoderm.
Conclusions:
- Equine trophectoderm differentiation, indicated by POU5F1 loss, is impaired in vitro but normalized by the uterine environment.
- Observed interspecies differences in trophectodermal POU5F1 expression may be partly due to in vitro culture artifacts.
- Failure of the uterine environment to correct in vitro-induced changes could contribute to placental abnormalities in transferred embryos.
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