Mechanistic mammalian target of rapamycin (MTOR) cell signaling: Effects of select nutrients and secreted phosphoprotein 1 on development of mammalian conceptuses

► Uterine epithelia secrete proteins and transport nutrients for conceptus development. ► Arginine and secreted phosphoprotein 1 (SPP1) activate MTOR cell signaling. ► Arginine metabolism to nitric oxide and polyamines stimulates conceptus growth. ► SPP1 induces focal adhesions between trophectoderm and uterine epithelia. ► Arginine and SPP1 stimulate conceptus development, implantation and pregnancy.