“…The cellular mechanisms involved in transplacental transport in the STB layer have been described in detail in a recent review and include: (i) Passive diffusion, which is governed by Fick's law and may occur with almost any compound with molecular weight less than 500 daltons; (ii) Facilitated or transporter‐mediated diffusion in which passive transport across the STB membranes and along a concentration gradient is enabled by molecular carriers in the STB membrane, for example, GLUTs for glucose or FATPs for fatty acids; (iii) Active transport against a concentration gradient, which requires energy supplied either by ATP hydrolysis (i.e., primary active transport), for example, protons, Ca 2+ and others , or by co‐transporters (i.e., secondary active transport), which themselves are transported down a concentration or electrochemical gradient such as SNATs for amino acids ; (iv) Phagocytosis and pinocytosis in its various forms allows internalization of macromolecules using a range of mechanisms. A well‐known example is the uptake of low‐density‐lipoprotein by receptor‐mediated endocytosis .…”