Definition of proamnion in US English:

proamnion

noun

Embryology
  • In many vertebrate embryos: an area of blastoderm, located at the cephalic end, in which there is no mesoderm separating the ectoderm and endoderm.

Origin

Late 19th century; earliest use found in American Naturalist. From pro- + amnion, after French proamnios.

Pronunciation

proamnion

/prəʊˈamnɪən/