Buccopharyngeal membrane
From Embryology
Introduction
(oral membrane) (Latin, bucca = cheek) A membrane that forms the external upper membrane limit (cranial end) of the early gastrointestinal tract (GIT). This membrane region first develops in the trilaminar embryo (week 3) during gastrulation. The "membrane" quality comes from being composed of only ectoderm and endoderm, without a middle (intervening) layer of mesoderm.
The membrane lies at the floor of the ventral depression (stomadeum) where the oral cavity will open and will breakdown to form the initial "oral opening" of the gastrointestinal tract. The equivilent membrane at the lower end of the gastrointestinal tract is the cloacal membrane.
