EDELMANN / SCIENCE PHOTO LIBRARY. EDELMANN / SCIENCE PHOTO LIBRARY.
The human embryo at around 4 weeks, showing the protective layers of the chorion & amnion surrounding the developing embryo (the outline of the embryo can be seen in middle of image). The outer membrane (chorion), develops from the mesoderm cells of the embryonic disc (the early embryo), & a portion later becomes the placenta (the organ which connects the foetus with the maternal blood circulation). The inner amnion encloses a fluid-filled sac, which absorbs shock, equalises pressure on the foetus, provides a barrier against microbes & prevents the foetus from adhering to its surroundings.
Model release not required. Property release not required.