Embryo‐Maternal Communication in Bovine – Strategies for Deciphering a Complex Cross‐Talk

Abstract

Early embryonic development, implantation and maintenance of a pregnancy are critically dependent on an intact embryo-maternal communication. So far, only few signals involved in this dialogue have been identified. In bovine and other ruminants, interferon tau is the predominant embryonic pregnancy recognition signal, exhibiting antiluteolytic activity. However, this is just one aspect of the complex process of embryo-maternal signalling, and a number of other systems are more likely to be involved. To gain a more comprehensive understanding of these important mechanisms, integrated projects involving specialists in embryology, reproductive biotechnology and functional genome research are necessary to perform a systematic analysis of interactions between pre-implantation stage embryos and oviduct or uterine epithelial cells, respectively. State-of-the-art transcriptomic and proteomic technologies will identify reciprocal signals between embryos and their maternal environment and the respective downstream reaction cascades. For in vivo studies, the use of monozygotic twins as recipient animals provides elegant model systems, thus eliminating genetic variability as a cause of differential gene expression. In addition, suitable systems for the co-culture of oviduct epithelial or endometrium cells with the respective embryonic stages need to be established for functional validation of candidate genes potentially involved in the dialogue between embryos and their maternal environment. The knowledge of these mechanisms should help to increase the pregnancy rate following embryo transfer and to avoid embryonic losses. Candidate genes involved in embryo-maternal communication will also be used to define new quality criteria for the selection of embryos for transfer to recipients. Another application is the supplementation of embryotrophic factors or components of embryo-maternal signalling in optimized formulations, such as bioartificial matrices. As a long-term goal, signalling mechanisms identified in bovine will also be functionally evaluated in other species, including the human.

Characterisation of endometrial gene expression and metabolic parameters in beef heifers yielding viable or non-viable embryos on Day 7 after insemination

“…While the oviductal environment has an important role in early embryonic development (Pushpakumara, et al 2002;Wolf 2003, Fenwick et al 2008) the main focus of this study was on the uterine component that affects early embryonic development. Alterations in the local uterine microenvironment can be one of the potential factors contributing to the subfertility in these heifers.…”

“…The oviduct is the first area of the reproductive tract through which the embryo passes on its way to the uterus and therefore can have an important impact on the development of the embryo (Wolf 2003;Fenwick et al 2008). In beef heifers however, there is clear evidence that the transcriptional profile of the uterine endometria is altered at different stages of the oestrous cycle (Mitko et al 2008) and during specific developmental stages of early pregnancy (Forde et al 2009a).…”

Caracterização das membranas fetais em búfalas no terço inicial da gestação

“…Existem quatro tipos de membranas fetais, o saco coriônico, o alantóide, o âmnion e o saco vitelínico (Wolf et al 2003).…”

Evaluation of laser-assisted lentiviral transgenesis in bovine

“…Oocytes contain mitochondrial DNA, which contributes to the genetic setting of an individual as well as the donor nucleus and can therefore, depending on the oocyte origin, vary (Han et al, 2004;Hiendleder et al, 2003). Three main steps are required for NT: 1) Removal of maternal chromatin from a recipient oocyte; 2)…”