Multiple-embryo transfer for studying very early maternal-embryo interactions in cattle.
In the present paper, we highlight the need to study very early maternal-embryo interactions and discuss how these interactions can be addressed. Bovine species normally carry one or, less frequently, two embryos to term; there are very rare cases of triplets or higher-order multiple pregnancies in which all the offspring are born alive. Multiple-embryo transfer (MET) in cattle allows for the detection of endometrial responses in scenarios where single-embryo transfer would not. Although MET is non-physiological, the present study shows that at the very early embryonic stages, a uterus carrying zona-enclosed embryos does not exhibit non-physiological reactions. On the contrary, MET should be considered the sum of multiple individual effects triggered by developing embryos. We provide arguments to support our hypothesis that describe a rationale for current work with MET, and we discuss alternative hypotheses. Using cattle as a model, we describe how technical approaches to analyzing zona-enclosed early embryo-maternal interactions (i.e., transcriptomics, proteomics, and endometrial cell culture) can help identify molecular changes that may be difficult to observe when only a single embryo is present. We conclude that MET can be used for studying very early maternal-embryo interactions in vivo in monotocous species. Free Spanish abstract: A Spanish translation of this abstract is freely available at http://www.reproduction-online.org/content/150/2/R35/suppl/DC1.
Centro de Biotecnología Animal - SERIDACamino de Rioseco 1225, La Olla - Deva, 33394 Gijón, Asturias, Spain egomez@serida.org.
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Gómez
Centro de Biotecnología Animal - SERIDACamino de Rioseco 1225, La Olla - Deva, 33394 Gijón, Asturias, Spain.
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Muñoz
D000818:Animals; D002417:Cattle; D004624:Embryo Transfer / Q000379:methods*; D004622:Embryo, Mammalian / Q000502:physiology; D047108:Embryonic Development / Q000502:physiology; D005260:Female; D005307:Fertilization in Vitro; D011247:Pregnancy; D011272:Pregnancy, Multiple / Q000235:genetics / Q000502:physiology*; D040901:Proteomics; D014599:Uterus / Q000502:physiology