Mouse embryo implantation is a highly invasive and controlled process that involves remodeling and degradation of the extracellular matrix of the uterus. Matrix metalloproteinases (MMPs) are the main proteinases facilitating this process. Extracellular matrix metalloproteinase inducer (EMMPRIN) can stimulate the production of MMPs and is required for successful implantation in the mouse. The aims of the present study were to examine the expression profiles of mRNA and proteins for EMMPRIN and MMPs in the developing mouse embryo in vitro, and to study whether EMMPRIN protein induces the production of MMPs by mouse blastocysts. EMMPRIN mRNA, detected by RT-PCR, was present at all stages of embryo development from the one-cell to the blastocyst outgrowth. EMMPRIN protein, observed by confocal microscopy, was present on the cell surface at the same stages of development as was the mRNA. Of seven MMPs studied, murine collagenase-like A (Mcol-A), murine collagenase-like B (Mcol-B) and gelatinase A (MMP-2) mRNAs were detected only in blastocyst outgrowths by RT-PCR. Gelatinase B (MMP-9) mRNA was detected both in expanded blastocysts and blastocyst outgrowths. MMP-2 and -9 proteins were detected in the cytoplasm of outgrowing trophoblast cells. Collagenase-2 (MMP-8), collagenase-3 (MMP-13), or stromelysin-1 (MMP-3) mRNAs were not present at any stage of pre- or peri-implantation mouse embryo development. Quantitative RT-PCR analyses showed that recombinant EMMPRIN protein did not stimulate MMP-2 or -9 expression by mouse blastocyst outgrowths. These data suggest that EMMPRIN may regulate physiological functions other than MMP production by mouse embryos during implantation.