Stomodeum
4782087
209257021
2008-04-30T16:33:46Z
151.112.37.162
{{Infobox Embryology |
Name = {{PAGENAME}} |
Latin = |
GraySubject = 241 |
GrayPage = 1101 |
Image = Gray977.png |
Caption = Human embryo about fifteen days old. [[Brain]] and [[heart]] represented from right side. [[Digestive tube]] and [[yolk sac]] in median section. (Stomodeum labeled in upper right.) |
Image2 = |
Caption2 = |
System = |
CarnegieStage = 9 |
Precursor = [[surface ectoderm]] |
GivesRiseTo = |
MeshName = |
MeshNumber = |
DorlandsPre = s_24 |
DorlandsSuf = 12760230 |
}}
The '''stomodeum''', also called '''stomatodeum''', is a depression between the [[brain]] and the [[pericardium]] in an [[embryo]], and is the precursor of the [[mouth]] and the anterior lobe of the [[pituitary gland]].
==Structure==
The stomodeum is lined by [[ectoderm]], and is separated from the anterior end of the [[fore-gut]] by the buccopharyngeal membrane.
This membrane is devoid of [[mesoderm]], being formed by the apposition of the stomodeal ectoderm with the fore-gut endoderm; at the end of the third week it disappears, and thus a communication is established between the mouth and the future [[pharynx]].
==Development==
The mouth is developed partly from the stomodeum, and partly from the floor of the anterior portion of the [[fore-gut]].
By the growth of the head end of the [[embryo]], and the formation of the [[cephalic flexure]], the [[pericardial area]] and the [[buccopharyngeal membrane]] come to lie on the ventral surface of the [[embryo]].
With the further expansion of the [[brain]], and the forward bulging of the [[pericardium]], the buccopharyngeal membrane is depressed between these two prominences. This depression constitutes the stomodeum.
No trace of the membrane is found in the adult; and the communication just mentioned must not be confused with the permanent isthmus faucium.
The [[lips]], [[teeth]], and [[gums]] are formed from the walls of the stomodeum, but the [[tongue]] is developed in the floor of the pharynx.
==Additional images==
<gallery>
Image:Gray40.png|Embryo between eighteen and twenty-one days.
Image:Gray44.png|Under surface of the head of a human embryo about twenty-nine days old.
Image:Gray45.png|Head end of human embryo of about thirty to thirty-one days.
</gallery>
==External links==
* [http://connection.lww.com/Products/sadler/images/figurelarge15-5.jpg Diagram at lww.com]
* {{EmbryologyUNC|hednk|015a}}
{{developmental-biology-stub}}
{{Gray's}}
{{Development of digestive system}}
[[de:Stomodeum]][[sv:Stomodeum]][[Category:Embryology]]