Another article describing the findings.
#YolkSac #DevBio #Embryos #Science #Medicine #scicomm #Development

https://phys.org/news/2023-08-multiple-functions-yolk-sac-revealed.html

AAAS: "Three organs in one? Researchers unscramble mysterious roles of human yolk sac." You may not be a chicken or duck-billed platypus, nonetheless you had a yolk sac during embryonic development. Researchers obtained yolk sac tissue from a biobank in UK, derived from embryos of 4 to 8 wks, + profiled gene activity at various stages. Four wks after conception, the yolk sac creates the first blood-forming stem cells + macrophages. "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." But the yolk sac is multifunctional, in that it also 'also carries proteins for breaking down harmful toxins and produces proteins necessary for blood clotting—a key ability in the early embryo.' Several enzymes have a role in lipid + sugar metabolism, which implies that despite lacking yolk the sac still provides nourishment. "Adults’ kidneys churn out erythropoietin, a hormone that stimulates formation of new red blood cells, and the yolk sac appears to be the early embryo’s source for the substance.' It is no joking matter to say the yolk sac performs jobs that will later be delegated to the liver, kidneys + bone marrow. No joking matter, hope you got that.   #embryology    #yolksac