A thin, tough, membranous sac that encloses the embryo or fetus of a mammal, bird, or reptile.It is filled with a serous fluid in which the embryo is suspended.
英
美
- 羊膜一层薄的、坚韧的膜囊，可包住哺乳动物、鸟类或爬行动物的胚胎或婴儿，膜囊被羊水充满，胚胎悬浮其中
