noun
- Membranous structure that functions as the circulatory system in mammalian embryos until the heart becomes functional.
- synonyms: vitelline sac, umbilical vesicle, vesicula umbilicus
- Membranous structure enclosing the yolk of eggs in birds, reptiles, marsupials, and some fishes; circulates nutrients to the developing embryo. .
WordNet 3.0 © 2006 by Princeton University
| APA | WordNet. (2010). yolk sac. Retrieved September 23, 2026, from http://smartdefine.org/yolk_sac/definitions/1194925 |
| Chicago | WordNet. 2010. "yolk sac" http://smartdefine.org/yolk_sac/definitions/1194925 (accessed September 23, 2026). |
| Harvard | WordNet 2010, yolk sac, Smart Define, viewed 23 September, 2026, <http://smartdefine.org/yolk_sac/definitions/1194925>. |
| MLA | WordNet. "yolk sac" 23 October 2010. Web. 23 September 2026. <http://smartdefine.org/yolk_sac/definitions/1194925> |