Dynamics of activities of matrix metalloproteinases-9 and -2, and the tissue inhibitors of MMPs in fetal fluid compartments during gestation and at parturition in the mare.

During late gestation in the mare, rapid fetal growth is accompanied by considerable placental growth and further invasion of the endometrium by microvilli. This growth requires extensive remodeling of the extracellular matrix (ECM). In early pregnancy, we know that matrix metalloproteinase (MMP)-9 and -2 are involved in the endometrial invasion during endometrial cup formation.