胚胎

例句：

1. 1. The embryonic development of the fetus is crucial for survival.
   胎儿的胚胎发育对生存至关重要。
2. 2. The study of embryonic development has important implications for medicine.
   胚胎发育研究对医学有重要影响。
3. 3. The early stages of a human embryo are still too fragile to be seen with the naked eye.
   人类胚胎的早期阶段仍然太脆弱，肉眼无法看见。