Media type: E-Article Title: Cdx1::Cre allele for gene analysis in the extraembryonic ectoderm and the three germ layers of mice at mid‐gastrulation Contributor: Hierholzer, Andreas; Kemler, Rolf Published: Wiley, 2009 Published in: genesis, 47 (2009) 3, Seite 204-209 Language: English DOI: 10.1002/dvg.20484 ISSN: 1526-954X; 1526-968X Keywords: Cell Biology ; Endocrinology ; Genetics Origination: University thesis: Footnote: Description: <jats:title>Abstract</jats:title><jats:p>Transgenic mice with a defined cell‐ or tissues‐specific expression of Cre‐recombinase are essential tools to study gene function. Here we report the generation and analysis of a transgenic mouse line (Cdx1::Cre) with restricted Cre‐expression from <jats:italic>Cdx1</jats:italic> regulatory elements. The expression of Cre‐recombinase mimicked the endogenous expression pattern of <jats:italic>Cdx1</jats:italic> at midgastrulation (from E7.5 to early headfold stage) inducing recombination in the three germlayers of the primitive streak region throughout the posterior embryo and caudal to the heart. This enables gene modifications to investigate patterning of the caudal embryo during and after gastrulation. Interestingly, we identified <jats:italic>Cdx1</jats:italic> expression in the trophectoderm (TE) of blastocyst stage embryos. Concordantly, we detected extensive Cre‐mediated recombination in the polar TE and, although to lesser extent, in the mural TE. In E7.5 postimplantation embryos, almost all cells of the extraembryonic ectoderm (ExE), which are derived from the polar TE, are recombined although the ExE itself is negative for Cdx1 and Cre at this stage. These results indicate that Cdx1::Cre mice are also a valuable tool to study gene function in tissues essential for placental development. genesis 47:204–209, 2009. © 2009 Wiley‐Liss, Inc.</jats:p>