As this is an anomaly of the first and second branchial arches
, most alterations are associated with structures developed from these arches, (28) presenting wide phenotypic variation.
aureus continued even after surgical removal of the gill rakers and microbranchiospines, indicating that the surfaces of the branchial arches
themselves are involved in the generation of inertial lift forces (Smith and Sanderson, 2007).
Within the branchial arches
, five pairs of ceratobranchials (cb) lie ventrally to four paired epibranchials and the pharyngobranchials (not shown).
Disruption of the vascular supply to first and second branchial arches
at about 30-40 days of gestation.
4B, C, G, H) occur on branchial arches
and also carry tiny teeth on bony tubercles (Fig.
However, in general, the branchial apparatus structures develop between the 4th and 6th week of gestation and consist of 6 pairs of mesodermal branchial arches
separated by 5 paired endodermal pharyngeal pouches internally and 5 paired ectodermal branchial clefts externally.
Other proposed theories are mesodermal dysplasia of Ist and IInd branchial arches
At the fifth week of fetal development, the first and second branchial arches
of the pharyngeal wall undergo a downward proliferation and meet the epicardial ridge, thereby closing the communication of the second, third, and fourth clefts with the exterior surface of the neck.
It results from failure of fusion of mandibular and maxillary processes of the first branchial arch (1) and so Tessier cleft 7 is also associated with anomalies of the structures arising from first and second branchial arches
According to the most recent hypothesis, it is caused by an impaired midline fusion of the first branchial arches
The dlx homobox gene codes for regional specification of branchial arches
and mutation in these genes is associated with the aberrant branchial arches
Of the six branchial arches
in humans, the fifth and sixth are rudimentary.