yolk sac
Học thuậtThân thiện
Definition
- Noun:
- A membranous sac enclosing the yolk in the eggs of birds, reptiles, marsupials, and some fish: This structure surrounds the nutrient-rich yolk and circulates nutrients to the developing embryo.
- A membranous structure in mammalian embryos: This structure functions as an early circulatory system, providing nutrients and aiding in blood cell formation until the fetal heart becomes functional.
Usage Examples
- Noun:
- The yolk sac is a vital source of nutrition for the chick before it hatches.
- In human development, the yolk sac is one of the first structures to form within the gestational sac.
Advanced Usage
- "Yolk sac tumor": A type of germ cell tumor that histologically resembles the embryonic yolk sac.
- The pathology report confirmed the presence of a yolk sac tumor.
Variants and Related Words
- Yolk (n): The yellow, nutrient-rich inner part of an egg.
- Separate the egg yolk from the white.
- Vitelline (adj): Pertaining to the yolk of an egg or the yolk sac.
- The vitelline duct connects the yolk sac to the midgut of the embryo.
Synonyms
- Vitelline sac: A technical synonym for the yolk sac.
Related Terms (Note: Not phrasal verbs or idioms, as this is a scientific term)
- Allantois: An extra-embryonic membrane involved in gas exchange and waste removal in bird and reptile eggs; in mammals, it contributes to bladder formation and the umbilical cord.
- Amnion: The innermost membrane that encloses the embryo of a mammal, bird, or reptile, containing the amniotic fluid.
Noun
- membranous structure enclosing the yolk of eggs in birds, reptiles, marsupials, and some fishes; circulates nutrients to the developing embryo
- membranous structure that functions as the circulatory system in mammalian embryos until the heart becomes functional