Figure 4From: New discoveries on the biology and detection of human chorionic gonadotropinThe differentiation of trophoblast cells in placental villi [54]. Fusion of villous cytotrophoblast cells is controlled by regular hCG [55]. Extravillous invasive cytotrophoblast cells produce hyperglycosylated hCG [44], while fused syncytiotrophoblast cells make regular hCG [40–42].Back to article page