产囊体

例句：

1. 1. The study of placental development is crucial for understanding human reproduction.
   研究胎盘发育对于理解人类生殖至关重要。
2. 2. During pregnancy, the placental transfers nutrients and oxygen to the fetus.
   怀孕期间，胎盘将营养物质和氧气传递给胎儿。
3. 3. Placental abruption is a condition where the placenta fails to properly attach tothe uterine wall.
   胎盘早剥是一种情况，其中胎盘未能适当附着在子宫壁上。