A pharyngeal groove (or branchial groove, or pharyngeal cleft
) is made up of ectoderm unlike its counterpart the
pharyngeal pouch on the
endoderm
Endoderm is the innermost of the three primary germ layers in the very early embryo. The other two layers are the ectoderm (outside layer) and mesoderm (middle layer). Cells migrating inward along the archenteron form the inner layer of the gastr ...
al side.
The first pharyngeal groove produces the
external auditory meatus
The ear canal (external acoustic meatus, external auditory meatus, EAM) is a pathway running from the outer ear to the middle ear. The adult human ear canal extends from the auricle to the eardrum and is about in length and in diameter.
Str ...
(ear canal).
The rest (2, 3, and 4) are overlapped by the growing
second pharyngeal arch, and form the floor of the depression termed the
cervical sinus
The cervical sinus is a structure formed during embryonic development. It is a deep depression found on each side of the neck. It is formed as the second pharyngeal arch (hyoid arch) grows faster than the other pharyngeal arches, so they become ...
, which opens ventrally, and is finally obliterated.
See also
*
Branchial cleft cyst
A branchial cleft cyst or simply branchial cyst is a cyst as a swelling in the upper part of neck anterior to sternocleidomastoid. It can, but does not necessarily, have an opening to the skin surface, called a fistula. The cause is usually a devel ...
*
Collaural fistula
References
Animal developmental biology
Pharyngeal arches
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