It generally represents an incidence of 1.7-2% within the branchial arches
malformations group , while some series report an incidence of less than 1% .
Resulting apoptosis and growth failure of the branchial arches
disrupt development of all its derivatives including the thymus.2 Moreover, RA induces its teratogenesis, via multiple pathways.
Ventral view of the hyoid and branchial arches
. a) Urotrygon munda, b) Urotrygon nana, c) Urotrygon chilensis, d) Urotrygon rogersi, e) Urotrygon aspidura.
Syndromes of the first and second branchial arches
, part 1: Embryology and characteristic defects.
Reduced blood flow and focal haemorrhage in the developmental region of the first and second branchial arches
in the blastogenesis period results in defect in mesoderm formation and its defective interaction with the neural crest cells .
Hemifacial microsomia (HM) is a congenital craniofacial malformation caused by hypoplasia of anatomical structures deriving from the first and second branchial arches
. As a result, HM involves facial skeleton, soft tissues, ear, and cranial nerves, thus resulting in the absence or insufficiency of these components .
Midline cleft of the lower lip is a rare congenital anomaly first described by Couronne in 1819 and was classified by Tessier as No 30 facial cleft.1 Midline cleft of the lower lip is not associated with any identified hereditary factors or gender predilection.1 Clinical presentation of these patients varies from a mild notching of the lower lip to complete midline cleavage of the inferior face, including bifurcation of the mandible, tongue and neck.2 There is occasional, associated deformities of soft tissue structures derived from the lower branchial arches
seen in these patients, there may be cleavage of the neck and manubrium sterni.3
(3,4) The tympanic ring appears first at the embryonic period from mesenchymal tissue lying between the first and second branchial arches
. (5,6) Multiple ossification centers join together to form an incomplete ring, opened above at the tympanic incisures.
DISCUSSION: Congenital cysts are dysembryogenetic lesions that can occur due to ectodermal elements getting entrapped during midline fusion of mesodermal elements of first and second branchial arches
, between 3rd and 4th weeks of intrauterine life.
Hemifacial microsomia (HFM) is a common birth defect involving structures derived from the first and second branchial arches
. Principal features include facial asymmetry, which is secondary to maxillary and mandibular hypoplasia, underdevelopment of the external ear preauricular skin tags or pits, and conductive hearing loss.
They feed, while swimming slowly with their mouths wide-open, allowing water and plankton to pass through the buccal cavity, into the pharynx and across the branchial arches
, which are lined with numerous gill rakers (1260 gill rakers per gill: Bigelow & Schroeder, 1948, p.
Pre-auricular sinus is a congenital malformation that is due to failure of the hillocks of the first and second branchial arches
(which form the auricle) to fuse completely.1,2 It was first described by Heusinger in 1864.2 It usually presents as a small opening in the skin anterior to the insertion of the helix.
They then characterized changes in the shape and position of the craniofacial structures, such as jaws, branchial arches
, eyes, otic capsules and olfactory pits, through "geometric morphometric analysis," which measured positioning of a total of 32 landmarks on the top and bottom sides of the tadpoles.