Gastrulation, the process where an embryo reorganizes itself from a hollow sphere into a multilayered structure, is considered a 'black box' of human development. This is because human embryos are typically not cultured for longer than 14 days because of bioethical concerns, and gastrulation occurs between 17- and 21-days post-fertilization. In addition, current stem cell models that mimic gastrulation have not been able to include the necessary extraembryonic tissues that give rise to the yolk sac and the placenta. Researchers now report a new method to develop 'peri-gastruloids,' an embryo-like structure that includes one of the supporting tissues, the yolk sac, missing from previous models.
from Top Health News -- ScienceDaily https://ift.tt/F0wcjh2