Y-Chromosome
wy KROH-muh-sohm
/waɪ ˈkroʊməˌsoʊm/
The sex-determining chromosome in most mammals; the presence of this chromosome typically triggers male development.
Yellow Bone Marrow
YEL-oh bohn MAIR-oh
/ˈjɛloʊ boʊn ˈmæroʊ/
Bone marrow that is yellow with fat; found at the ends of long bones in adults.
Yolk Sac
yohk sak
/joʊk sæk/
A membranous sac attached to an embryo, providing early nourishment and the first site of blood cell formation.