leptotene stage

例句：

1. 1. The researchers found that the leptotene stage is crucial for embryonicdevelopment.
   研究人员发现，卵黄期对于胚胎发育至关重要。
2. 2. During the leptotene stage, the egg membranes arestill fragile and vulnerable to damage.
   在卵黄期，蛋膜仍然脆弱易受损伤。
3. 3. The leptotene stageis a critical period during which the embryo's development can be influenced by externalfactors.
   卵黄期是胚胎发育可能受到外界因素影响的关键时期。