肠胚

例句：

1. 1. The fetus is the first stage of a developing embryo.
   胎儿是胚胎发展的第一阶段。
2. 2. The early stages of development are crucial for the growth and survival of the fetus.
   胚胎早期的发展对胎儿的生长和存活至关重要。
3. 3. The study of embryology helps us understand how the human body is formed from the fertilized egg.
   胚胎学的研究帮助我们理解人体是如何从受精卵形成的。