Hemifacial microsomia in pediatric patients: asymmetric abnormal development of the first and second branchial arches
Fish were anesthetized with MS-222, and the tissue supporting all lateral and medial rakers and microbranchiospines was removed with microforceps from the anterior four branchial arches
on both sides of five fish (Smith and Sanderson, 2007).
7N-U) on the branchial arches
are oriented with the base towards the gill filaments.
Anomalies of the first, second, and third branchial arches
have been commonly described.
5) It consists of (5) paired branchial arches
& each separated externally by ectodermal clefts and internally by endodermal pouches.
3,4) In 1997, Vieille-Grosjean et al showed for the first time that at 4 weeks of development, human branchial arches
express the paralogous groups using the mouse homologues of HOXB1, HOXA2, HOXB2, HOXA3, HOXB3, HOXD3, HOXB4, and HOXC4 as probes for in situ hybridization.
The cartilaginous structures of the larynx are derived from the fourth and sixth pairs of branchial arches
and begin their development in the fifth week of gestation.
By the sixth week of intrauterine development, the embryo exhibits paired branchial arches
By the end of the 4th week of embryonic life, the branchial arches
(derived from neural crest cells) and the mesenchyme (derived from the lateral mesoderm) are easily recognizable.
5) They are thought to arise from unsegmented mesoderm in the branchial arches
Congenital type is due to entrapment of ectodermal substance between the midline fusion of first and second branchial arches
during third and fourth intrauterine life.
It appears' to occur as a result of a failure of fusion of the paired second branchial arches
in the midline during embryogenesis.