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).
Within the branchial arches
, five pairs of ceratobranchials (cb) lie ventrally to four paired epibranchials and the pharyngobranchials (not shown).
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.
According to the most recent hypothesis, it is caused by an impaired midline fusion of the first branchial arches
. (5) Histologically, the lesion consists of skeletal muscle, a fibrous cord, and exocrine tissue.
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.
Of the six branchial arches
in humans, the fifth and sixth are rudimentary.
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.
By the sixth week of intrauterine development, the embryo exhibits paired branchial arches
. Each arch is formed by mesenchyme from both somitic mesoderm and neural crest mesoderm.
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.
(5) They are thought to arise from unsegmented mesoderm in the branchial arches
. (8) Most reported cases of extracardiac rhabdomyoma have involved solitary masses; the few that have occurred multifocally were associated with no clinically significant difference in treatment or outcome.