http://upload.wikimedia.org/wikipedia/commons/9/93/Gray977.png

consider indicating location. e.g. anterior. Note some AOs place this as part of oral opening, but it's not clear when this structure comes into existence

Anterior part of the embryonic alimentary canal formed as an invagination of the ectoderm; the future mouth.[TAO], the primordial mouth region of the developing head, initially a midline ectodermal depression between the forebrain bulge (cranially) and the heart bulge (caudally) and between the maxillary and mandibular components of the first pharyngeal arch; the stomodeum is separated from the anterior end of the foregut by the buccopharyngeal membrane; the mouth is developed partly from the stomodeum, and partly from the floor of the anterior portion of the foregut; the lips, teeth, and gums are formed from the walls of the stomodeum, but the tongue is developed in the floor of the pharynx

stomodeal-hypophyseal primordium

uberon

mouth pit, oral pit, oral ectoderm

stomodeal

UBERON:0000930

This class groups together disparate structures as all being the anterior part of the early metazoan digestive tract and precursor of the mouth. However, the developmental processes vary, so this class may be split in future. E.g. in mammals it is a rostral depression surrounded by prominences. Outgrowth of the prominences produces a stomodeal cavity.

• stomodeal lumen

• future mouth

• calcareous tooth

• stomatodeum gland
• stomodeal lumen