Henry Gray (1825–1861). Anatomy of the Human Body. 1918.
FIG. 29
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| Diagram of a transverse section, showing the mode of formation of the amnion in the chick. The amniotic folds have nearly united in the middle line. (From Quain’s Anatomy.) Ectoderm, blue; mesoderm, red; entoderm and notochord, black. |