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Specifically, this syndrome affects the first branchial (or pharyngeal) arch, which is the precursor of the maxilla and mandible. Because the branchial arches are important developmental features in a growing embryo , disturbances in their development create lasting and widespread effects.
The first pharyngeal arch, also mandibular arch (corresponding to the first branchial arch of fish), is the first of six pharyngeal arches that develops during the fourth week of development. [10] It is located between the stomodeum and the first pharyngeal groove .
The branchial system is typically used for respiration and/or feeding. Many fish have modified posterior gill arches into pharyngeal jaws, often equipped with specialized pharyngeal teeth for handling particular prey items (long, sharp teeth in carnivorous moray eels compared to broad, crushing teeth in durophagous black carp).
Apert syndrome is a form of acrocephalosyndactyly, a congenital disorder characterized by malformations of the skull, face, hands and feet. It is classified as a branchial arch syndrome, affecting the first branchial (or pharyngeal) arch, the precursor of the maxilla and mandible.
Originally it was the lower of two cartilages which supported the first branchial arch in early fish. Then it grew longer and stronger, and acquired muscles capable of closing the developing jaw. [1] In early fish and in chondrichthyans (cartilaginous fish such as sharks), Meckel's cartilage continued to be the main component of the lower jaw.
First arch syndromes are congenital defects caused by a failure of neural crest cells to migrate into the first pharyngeal arch. [1] They can produce facial anomalies . Examples of first arch syndromes include Treacher Collins syndrome and Pierre Robin syndrome .
The cause of Goldenhar syndrome is largely unknown. However, it is thought to be multifactorial, although there may be a genetic component, which would account for certain familial patterns. It has been suggested that there is a branchial arch development issue late in the first trimester. [citation needed]
Histologic slide showing a tooth bud. A: enamel organ B: dental papilla C: dental follicle. The tooth germ is an aggregation of cells that eventually forms a tooth. [2] These cells are derived from the ectoderm of the first pharyngeal arch and the ectomesenchyme of the neural crest.