Figure 2. Routes of exit of cholesterol from trophoblasts and fetal endothelial cells. Cholesterol exits these cells by being effluxed out of cells to acceptors in the plasma or by being secreted. There are several routes for efflux to occur, and all proteins involved have been found in the cell types listed; aqueous diffusion to acceptors (with lipid-poor acceptors being most efficient), SR-BI mediated, ABCG1-mediated, and ABCA1-mediated. In trophoblasts, studies have shown that cells can secrete lipoproteins and apolipoproteins which will carry sterols to the circulation as they exit the cell. Finally, exosomes carry cholesterol as they exit cells.