placental barrier

例句：

1. 1. The placental barrier is crucial for the development ofthe fetus.
   胎盘屏障对胎儿的发展至关重要。
2. 2. Researchers are studying the function ofthe placental barrier in pregnancy.
   研究人员正在研究胎盘屏障在怀孕期间的功能。
3. 3. Theplacental barrier allows the mother's immune system to protect the baby fromharmful substances.
   胎盘屏障允许母亲的免疫系统保护婴儿免受有害物质的伤害。