yolk sac

例句：

1. 1. The baby chick is developing its yolking sac.
   小鸡正在发育它的卵黄囊。
2. 2.The doctor removed the damaged yolking sac to save the patient's life.
   医生取出了损坏的卵黄囊以挽救病人的生命。
3. 3. The researchers found that the yolking sac plays a crucial role in embryonic development.
   研究人员发现卵黄囊在胚胎发育中起着至关重要的作用。