Dictionary.net

• The superficial layer of decidual tissue in the pregnant uterus, in which the interglandular tissue preponderates.

1920 - A practical medical dictionary.
By Stedman, Thomas Lathrop

• The surface layer of the decidua vera, constituting about one-fourth of the entire thickness.

1920 - A dictionary of scientific terms.
By Henderson, I. F.; Henderson, W. D.