Fig. 2

ETCHbox organisation and expression in preimplantation development: a The Crxos locus has undergone a mouse-specific duplication and generates three transcripts: two with a single homeobox and a composite double-homeobox transcript. Crxos is the Tprx1 orthologue although originally named as a distinct gene. b Analysis of protein and nucleotide sequences of 66 Obox genes in mouse identified four groupings; sequences and expression profiles enable OboxA to be split into three subgroups. c The three Crxos transcripts have the same preimplantation temporal expression pattern, with the 3′ single-homeobox transcript generally having higher RNA levels