nutritive yolk

nutritive yolk
accessory y.

Medical dictionary. 2011.

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  • Yolk sac — Not all yolk has to do with birds’ eggs. Human embryos have a yolk sac, a membrane outside the embryo but connected by a tube (the yolk stalk) though the umbilical opening to the embryo’s midgut. The yolk sac serves as an early site for …   Medical dictionary

  • yolk sac — noun Date: 1861 a membranous sac of most vertebrates that encloses the yolk, is attached in most forms (as in humans) through the yolk stalk with the intestinal cavity of the embryo, and is supplied with blood vessels that transport nutritive… …   New Collegiate Dictionary

  • yolk — /joʊk / (say yohk) noun 1. the yellow and principal substance of an egg, as distinguished from the white. 2. Biology that part of the contents of the egg of an animal which enters directly into the formation of the embryo (formative yolk or… …  

  • Yolk sac — Infobox Embryology Name = Yolk sac Latin = GraySubject = 11 GrayPage = 54 Caption = Human embryo of 2.6 mm. Caption2 = Human embryo from thirty one to thirty four days System = CarnegieStage = 5b Days = 9 Precursor = endoderm GivesRiseTo =… …   Wikipedia

  • yolk sac — noun 1. membranous structure that functions as the circulatory system in mammalian embryos until the heart becomes functional • Syn: ↑vitelline sac, ↑umbilical vesicle, ↑vesicula umbilicus • Hypernyms: ↑sac 2. membranous structure enclosing the… …   Useful english dictionary

  • yolk — yolked, adj. yolkless, adj. yolky, adj. /yohk, yohlk/, n. 1. the yellow and principal substance of an egg, as distinguished from the white. 2. Embryol. the part of the contents of the egg of an animal that enters directly into the formation of… …   Universalium

  • yolk sac — Embryol. 1. an extraembryonic membrane that encloses the yolk of eggs in birds, reptiles, and marsupials and that circulates nourishment from the yolk to the developing embryo. 2. a similar membrane in placental mammals that encloses a mostly… …   Universalium

  • yolk — also yoke noun Etymology: Middle English yolke, from Old English geoloca, from geolu yellow more at yellow Date: before 12th century 1. a. the yellow spheroidal mass of stored food that forms the inner portion of the egg of a bird or reptile and… …   New Collegiate Dictionary

  • yolk — 1. One of the types of nutritive material stored in the ovum for the nutrition of the embryo; y. is particularly abundant and conspicuous in the eggs of birds. SYN: vitellus. 2. Fatty material found in the wool of sheep; when extracted and… …   Medical dictionary

  • Ovum — For other uses, see Ovum (disambiguation). Ovum A human ovum with corona radiata surrounding it An ovum (plural ova, from the Latin word ovum meaning egg …   Wikipedia

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