| 释义 |
yolk sacn.（名词）- A membranous sac attached to an embryo, providing early nourishment in the form of yolk in bony fishes, sharks, reptiles, birds, and primitive mammals and functioning as the circulatory system of the human embryo before internal circulation begins.卵黄囊：一种附在胚胎上的薄膜囊，在硬骨鱼、鲨、爬行动物、鸟类和原始哺乳动物内以卵黄的形式提供早期营养物，在内部循环开始之前，作为人类胚胎的循环系统
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