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An area of the extraembryonic membranes beneath, and in front of, the developing head of a young embryo that remains without mesoderm for some time.
Farlex Partner Medical Dictionary © Farlex 2012
proamnion(prō-ăm′nē-ŏn) [Gr. pro, before, + amnion, amnion]
A region anterior to the head in a vertebrate embryo in which mesoderm is lacking.
Medical Dictionary, © 2009 Farlex and Partners