yolk sac

yolk sac
a sac containing yolk used for nourishment in larval fish

Dictionary of ichthyology. 2009.

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  • yolk sac — n. Zool. 1. a saclike vascular membrane containing yolk, an outgrowth from the ventral surface of very yolky vertebrate embryos, as those of fishes, birds, or reptiles, that supplies nourishment to the embryo 2. a homologous organ in most… …   English World dictionary

  • yolk sac — yolk′ sac n. dvl an extraembryonic membrane that encloses the yolk of eggs • Etymology: 1860–65 …   From formal English to slang

  • yolk sac — yolk sac. См. желточный мешок. (Источник: «Англо русский толковый словарь генетических терминов». Арефьев В.А., Лисовенко Л.А., Москва: Изд во ВНИРО, 1995 г.) …   Молекулярная биология и генетика. Толковый словарь.

  • 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 — 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 sac — thin membrane which surrounds the yolk of an egg and supplies nutrients to the embryo (in mammals, the yolk sac ceases to function when the placenta forms) …   English contemporary dictionary

  • yolk sac tumor — a malignant germ cell tumor of children that represents a proliferation of both yolk sac endoderm and extraembryonic mesenchyme. It is characterized by a labyrinthine glandular pattern with a papillary projection into a sinuslike space;… …   Medical dictionary

  • yolk-sac larva — a fish larva which has already hatched from the egg but has not started feeding yet and still absorbs the yolk in the ventrally attached yolk sac. At the end of this stage in development, the yolk and oil globule(s) have been used up, the major… …   Dictionary of ichthyology

  • yolk-sac placenta — the yolk sac helps in formation of a placenta which allows a connection of the embryo to the mother for nourishment …   Dictionary of ichthyology

  • yolk sac endoderm — the epithelial lining of the yolk sac …   Medical dictionary

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