Wordnet polsko-angielski 
                         (membranous structure that functions as the circulatory system in mammalian embryos until the heart becomes functional) 
yolk sac, vitelline sac, umbilical vesicle, vesicula umbilicus 
Słownik medyczny polsko-angielski Iwona Kienzler
                        vitelline sac, yolk sac, umbilical vesicle