Complex sentence: Because glucose travels across the placenta (through diffusion facilitated by GLUT1 carrier), which is located in the syncytiotrophoblast on both the microvillus and basal membranes; they may be the rate-limiting step in placental glucose transport.
Split into simpler sentences: Because glucose travels across the placenta (through diffusion facilitated by GLUT1 carriers), which is located in the syncytiotrophoblast. GLUT1, is located on both the microvillus and basal membranes and they may be the rate-limiting step in placental glucose transport.