Day 12 (1p21.3-1p21.1): Tissue factor, a protein that senses bleeding

Day 12 has 32 protein-coding genes including F3, also known as coagulation factor III, thromboplastin, or tissue factor. F3 protein is expressed on the surface of cells that ordinarily should not be exposed to blood. When bleeding occurs and F3 is exposed to the blood, a series of clotting reactions is activated.

F3 is found throughout bony vertebrates, so it is at least 440 million years old.

Click here to see your F3 gene.