Two Novel Mechanistic Paradigms in Pig Pregnancy: I. Osteopontin Binds to the ITGAV (the αv Integrin Subunit) to Promote Porcine Endothelial Progenitor Cell Incorporation into Developing Vasculature. II. Expression and Regulation of Genes for Glucose and Arginine Transporters in Pig Uteri, Conceptuses and Placentae Increases during Pregnancy.