umbilical vesicle
— Navneord
– Engelsk
~ membranous structure that functions as the circulatory system in mammalian embryos until the heart becomes functional
Urban VI
— Navneord
– Engelsk
~ Italian pope from 1378 to 1389 whose contested election began the Great Schism; he alienated his political allies by his ruthless treatment of his opponents (1318-1389)