dart sac

• 射囊

dart sac的用法和样例：

例句

1. The peritoneal cavity is a closed sac.
   腹膜腔是一个封闭的囊腔。
2. Abnormal development was observed at tetrad and mature embryo sac.
   在四分体和成熟胚囊时期观察到了异常发育现象。