| 单词 | yolk sac |
| 例句 | They took no food, living on the large yolk sac. Silent Spring 1962-09-27T00:00:00Z What is important is that gastruloids recapitulate some features of early development even without the external cues from the placenta or yolk sac that typically direct the organization of an early embryo. Small Collections of Cells Determine How a Body Takes Its Shape 2023-11-09T05:00:00Z There is a yolk sac, which has some of the roles of the liver and kidneys, and a bilaminar embryonic disc - one of the key hallmarks of this stage of embryo development. Scientists grow whole model of human embryo, without sperm or egg 2023-09-06T04:00:00Z Like chickens, duck-billed platypuses, and other animals that hatch from eggs, you had a yolk sac when you were an embryo. Three organs in one? Researchers unscramble mysterious roles of human yolk sac 2023-08-16T04:00:00Z Each team’s models vary in the techniques used and how complete they are, he said, with some mirroring not just the embryo but the very beginnings of the placenta and yolk sac, too. Scientists use stem cells to create models of human embryos and study our earliest days 2023-06-27T04:00:00Z Dr. Mo Ebrahimkhani, a developmental biologist at the University of Pittsburgh, and his colleagues observed the formation of a yolk sac in their experiment, for example. Scientists Debut Lab Models of Human Embryos 2023-06-24T04:00:00Z And the second stem cell type forms hypoblastlike tissue, and it’s a tissue that will make a yolk sac. Scientists Create Human Embryo-like Structures with Stem Cells 2023-06-16T04:00:00Z While the inner amniotic membrane surrounds the embryo itself, the chorion surrounds the embryo and yolk sac. Fundamentals of Biology 2015-01-01T00:00:00Z However, the function of the human yolk sac is unclear. Three organs in one? Researchers unscramble mysterious roles of human yolk sac 2023-08-16T04:00:00Z That model contains embryonic tissues and tissues that can go on to produce structures surrounding the embryo such as the placenta and yolk sac. Scientists use stem cells to create models of human embryos and study our earliest days 2023-06-27T04:00:00Z Out of the yolk sac, they even observed the development of progenitors of blood cells. Scientists Debut Lab Models of Human Embryos 2023-06-24T04:00:00Z The researchers also found signs that blood cells and their components were beginning to take shape in the yolk sac, which supplies embryos with nutrients. Lab-Grown Monkey Embryos Reveal in 3-D How Organs Begin 2023-05-15T04:00:00Z Then, a few years ago, her team discovered that when they added stem cells that give rise to the placenta and yolk sac, their embryos developed further. Mouse Embryos Grown without Eggs or Sperm 2022-08-26T04:00:00Z Now, a study out in Science today reveals the human yolk sac stands in for organs such as the liver and kidneys that arise later in development. Three organs in one? Researchers unscramble mysterious roles of human yolk sac 2023-08-16T04:00:00Z The embryo envelops a portion of the yolk sac, which protrudes with the umbilical cord from what will become the abdomen. Anatomy and Physiology 2013-06-19T00:00:00Z Given the context of the article, I am assuming that the writer meant to say “yolk sac” rather than “yoke sac” and that the eagles “have learned to adapt” rather than “adopt” to urban life. Opinion | Readers critique The Post: What wasn’t mentioned about D.C.’s ‘pot-gifting’ businesses 2022-04-15T04:00:00Z Although its cause is not precisely known, it's thought it may be caused by chromosomal abnormalities, intrauterine drug exposure or the rupturing of a fetal membrane or yolk sac. Albino baby turtle born with heart outside its body 2019-02-18T05:00:00Z These ‘blastoids’ contain analogues of the three cell lineages thought to form the embryo, placenta and yolk sac. Debate ethics of embryo models from stem cells 2018-12-11T05:00:00Z There’s been “a dearth of studies on the human yolk sac,” says developmental biologist Anthony Carter of the University of Southern Denmark, who wasn’t connected to the research. Three organs in one? Researchers unscramble mysterious roles of human yolk sac 2023-08-16T04:00:00Z Blood cells and vessel production in structures outside the embryo proper called the yolk sac, chorion, and connecting stalk begin about 15 to 16 days following fertilization. Anatomy and Physiology 2013-06-19T00:00:00Z Analysis of the labelled cells revealed that EMPs actively migrate from the yolk sac into the embryo and differentiate into endothelial cells — reverting to their initial endothelial fate but now in an intraembryonic site. A dual origin for blood vessels 2018-09-25T04:00:00Z Internally, cells seemed to develop into precursors of the embryo proper and yolk sac — an early structure supplying blood to the embryo. The labs growing human embryos for longer than ever before 2018-07-03T04:00:00Z Red lines indicate cell death and loss of yolk sac vascularization phenotype. LUBAC is essential for embryogenesis by preventing cell death and enabling haematopoiesis 2018-04-24T04:00:00Z Although the yolk sac never produces its namesake substance in most mammals, it’s not vestigial. Three organs in one? Researchers unscramble mysterious roles of human yolk sac 2023-08-16T04:00:00Z Some grow to form the extra-embryonic membranes needed to support and protect the growing embryo: the amnion, the yolk sac, the allantois, and the chorion. Anatomy and Physiology 2013-06-19T00:00:00Z But in the human embryo knockouts, placental cells and yolk sac cells also failed to form. Scientists use gene-editing technology to knock out genes in human embryos for first time 2017-09-20T04:00:00Z However, the researchers say their artificial embryo is unlikely to develop into a healthy foetus as it would probably need the third form of stem cell, which develops into the yolk sac that provides nutrition. Artificial 'embryos' created in the lab - BBC News 2017-03-02T05:00:00Z Green line indicates mild cell death phenotype without loss of yolk sac vascularization. LUBAC is essential for embryogenesis by preventing cell death and enabling haematopoiesis 2018-04-24T04:00:00Z In mice, the yolk sac manufactures the embryo’s first blood cells and relays nutritious molecules produced by the uterus. Three organs in one? Researchers unscramble mysterious roles of human yolk sac 2023-08-16T04:00:00Z Figure 28.8 Development of the Embryonic Disc Formation of the embryonic disc leaves spaces on either side that develop into the amniotic cavity and the yolk sac. Anatomy and Physiology 2013-06-19T00:00:00Z Strangely, these late-term embryos also had swollen bellies, which were initially thought to be yolk sacs, a form of stored food. In Many Species, a Family Dinner Means Something Else 2017-01-30T05:00:00Z Students will start feeding the fish once their yolk sacs are depleted. Elementary students raise trout in classrooms 2017-01-27T05:00:00Z For example, the cells that develop into the fetus and the yolk sac diverge later in human embryos. Why this lab-grown human embryo has reignited an old ethical debate 2016-05-04T04:00:00Z And in some tissues of adult rodents, the immune cells known as macrophages are descended from yolk sac cells, not the bone marrow cells that give rise to most macrophages. Three organs in one? Researchers unscramble mysterious roles of human yolk sac 2023-08-16T04:00:00Z The yolk sac supplies some nutrients absorbed from the trophoblast and also provides primitive blood circulation to the developing embryo for the second and third week of development. Anatomy and Physiology 2013-06-19T00:00:00Z Further investigation showed that the abdominal bumps were not yolk sacs at all — they were stomachs full of smaller fetal sharks. In Many Species, a Family Dinner Means Something Else 2017-01-30T05:00:00Z During that time, it undergoes several physiological adaptations, including absorbing the yolk sac within its body and fully inflating its lungs. Before Eagles Fly, They Must Hatch 2016-04-04T04:00:00Z After normal implantation, part of a mammalian embryo reorganizes itself into what will become the placenta and the yolk sac. Why this lab-grown human embryo has reignited an old ethical debate 2016-05-04T04:00:00Z The data confirmed that a human embryo also makes its first blood cells in the yolk sac. Three organs in one? Researchers unscramble mysterious roles of human yolk sac 2023-08-16T04:00:00Z Together, the stalks of the yolk sac and allantois establish the outer structure of the umbilical cord. Anatomy and Physiology 2013-06-19T00:00:00Z “At this point, their yolk sacs are still attached,” he said. Winchester students release trout at Red River Gorge 2015-05-10T04:00:00Z But at comparatively low concentrations, the scientists wrote, 50 percent or more of tuna still developed fluids around their hearts and yolk sacs. Fish Embryos Exposed to Oil From BP Spill Develop Deformities, a Study Finds 2014-03-25T00:29:39Z Unlike neurons and other glial cells, they begin in the embryonic yolk sac as immune-cell progenitors, just as the macrophages that patrol the bloodstream for foreign invaders do. Microglia: The constant gardeners 2012-05-30T17:50:34.540Z The team also discovered that the yolk sac uses an unexpected shortcut to produce macrophages. Three organs in one? Researchers unscramble mysterious roles of human yolk sac 2023-08-16T04:00:00Z The first layer is the endoderm, a sheet of cells that displaces the hypoblast and lies adjacent to the yolk sac. Anatomy and Physiology 2013-06-19T00:00:00Z The external gills are long and filamentous, and the yolk sac is large. Neotropical Hylid Frogs, Genus Smilisca 2011-10-24T02:00:14.853Z Subsequent retraction or rupture of the yolk sac and closure of the navel are accompanied by a decrease in height of shell and slight, further widening of the carapace. Natural History of the Ornate Box Turtle, Terrapene ornata ornata Agassiz 2011-10-01T02:00:30.200Z “At this stage, and for the first three weeks of its existence, the embryo is a ‘flat disc floating on the surface of the yolk sac.’ Embryology The Beginnings of Life 2011-09-12T02:00:28.483Z As one of these immune cells matures, it usually goes through an intermediate stage known as a monocyte, but the yolk sac macrophages bypass this step. Three organs in one? Researchers unscramble mysterious roles of human yolk sac 2023-08-16T04:00:00Z Four embryonic membranes form to support the growing embryo: the amnion, the yolk sac, the allantois, and the chorion. Anatomy and Physiology 2013-06-19T00:00:00Z The external gills are moderately long, slender, and filamentous; the yolk sac is still moderately large. Neotropical Hylid Frogs, Genus Smilisca 2011-10-24T02:00:14.853Z A turtle that hatched with a large yolk sac in a natural nest possibly would benefit, through increased ease of mobility, if the yolk sac ruptured. Natural History of the Ornate Box Turtle, Terrapene ornata ornata Agassiz 2011-10-01T02:00:30.200Z It is in this region, and in that of the yolk sac which lies just underneath it, that the future growth of the embryo itself occurs, and the portion is therefore termed the “embryonic area.” Embryology The Beginnings of Life 2011-09-12T02:00:28.483Z The scientists also tested whether, like in mice, yolk sac–derived macrophages are still present in adult tissues. Three organs in one? Researchers unscramble mysterious roles of human yolk sac 2023-08-16T04:00:00Z Upper row: Ventral views showing scar of yolk sac and ventral side of wing. The Postnatal Development of Two Broods of Great Horned Owls Bubo virginianus 2011-02-02T03:00:24.983Z Figures to illustrate the relative function and importance of allantois and yolk sac in bird and mammal. Text Book of Biology, Part 1: Vertebrata Autopsy revealed a vestige of the retracted yolk sac, approximately one millimeter in diameter, on the small intestine. Natural History of the Ornate Box Turtle, Terrapene ornata ornata Agassiz 2011-10-01T02:00:30.200Z This point is where the communication exists between the inside of the tube, which is the embryo, and the yolk sac. Embryology The Beginnings of Life 2011-09-12T02:00:28.483Z The versatile yolk sac “is three organs in one,” she says, performing jobs that will later be delegated to the liver, kidneys, and bone marrow. Three organs in one? Researchers unscramble mysterious roles of human yolk sac 2023-08-16T04:00:00Z As development progresses, the yolk sac hands over this job to the forming liver, which then passes it to the bone marrow, the birthplace of blood cells in adults. Three organs in one? Researchers unscramble mysterious roles of human yolk sac 2023-08-16T04:00:00Z We even find a yolk sac with no yolk in it. Text Book of Biology, Part 1: Vertebrata Desire to feed varied in hatchlings of the same brood and seemed not to be correlated with retraction of the yolk sac or retention of the caruncle. Natural History of the Ornate Box Turtle, Terrapene ornata ornata Agassiz 2011-10-01T02:00:30.200Z As in other species, the human yolk sac is a multitasker, the study shows. Three organs in one? Researchers unscramble mysterious roles of human yolk sac 2023-08-16T04:00:00Z One challenge of using such mimics is that they stop developing at early stages, but ensuring that the yolk sac is present may allow them to progress further. Three organs in one? Researchers unscramble mysterious roles of human yolk sac 2023-08-16T04:00:00Z The yolk sac retracts mainly between the time when the egg shell is first punctured and the time when the turtle actually emerges from the shell. Natural History of the Ornate Box Turtle, Terrapene ornata ornata Agassiz 2011-10-01T02:00:30.200Z But the allantois and yolk sac of the rabbit, though they correspond in development, differ entirely in function from the similar organs of the fowl. Text Book of Biology, Part 1: Vertebrata When hatching is completed, the yolk sac usually protrudes no more than two millimeters, but in some individuals it is large and retracts slowly over a period of several days. Natural History of the Ornate Box Turtle, Terrapene ornata ornata Agassiz 2011-10-01T02:00:30.200Z The yolk sac retracts mainly during hatching; it sometimes ruptures after hatching. Natural History of the Ornate Box Turtle, Terrapene ornata ornata Agassiz 2011-10-01T02:00:30.200Z Whether the human yolk sac takes on other tasks—in some species, for example, it transfers maternal antibodies to embryos—remains to be seen. Three organs in one? Researchers unscramble mysterious roles of human yolk sac 2023-08-16T04:00:00Z The yolk sac is of the very smallest nutritive value; instead of being the sole source of food, its contents scarcely avail the young rabbit at all as nourishment. Text Book of Biology, Part 1: Vertebrata |
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