Exam 2 Colombo Pharyngeal Development, Genetics, and Defects Flashcards
Folding of the embryo during gastrulation results in:
An embryo where the endoderm is separated from the ectoderm, except at the 2 ends (tonsillar pillars)
The arches appear at around __ weeks of development
4
Where does the stomodeum form?
just above the first arch and near the maxillary prominence
The ____ and the _____ form around stomodeum
mandible and maxilla
The outside lining of each arch is made of:
ectoderm (where the groove is)
The inside lining of each arch is:
endoderm (where the pouch is)
Where is mesoderm and neural crest cells found in each arch?
Mesoderm between endoderm and ectoderm, neural crest is around/migrates throughout the mesoderm
What is a pharyngeal groove?
indent formed externally by two arches
What is a pharyngeal pouch?
Indent formed internally between 2 arches
What is a pharyngeal membrane?
Membrane between ectoderm of groove and endoderm of pouch
The arches are formed from what embryonic germ tissue layers?
- ectoderm
- endoderm
- mesoderm
3.5. Neural crest
Cranial nerve __ is associated with arch 1
5
Cranial nerve __ is associated with arch 2
7
Cranial nerve __ is associated with arch 3
9
Cranial nerve __ is associated with arch 4
10
The malleus and incus are derived from:
Arch 1
The stapes is derived from:
Arch 2
Styloid process is derived from:
Arch 2
Stylohyoid ligament is derived from:
Arch 2
Thyroid cartilage is derived from:
Arch 3 and 4
Cricoid cartilage is derived from:
Arch 4
Meckel’s cartilage serves as a:
Massive signaling device (drives the formation of the mandible)
Meckel’s cartilage is derived from:
Arch 1
What bones of the head/face form from intramembranous ossification?
Temporal bone, zygomatic bone, maxilla, mandible
What bones of the head/face form from endochondral ossification?
Ossicles (malleus, incus, stapes)
The mandible forms _____ to Meckel’s cartilage
Lateral
How many Meckel’s cartilages are there?
2; they are not continuous - separated at the midline by a little band of mesenchymal tissue
During the formation of the mandible, CN ___ runs along Meckel’s cartilage and branches into _____
5; lingual and inferior alveolar
During the formation of the mandible, what occurs around the final branching of the IA nerve?
Mesenchyme condenses around, spreads along Meckel’s cartilage
During the formation of the mandible, bone forms around:
the IA, forming the mandibular canal
Muscles of mastication are derived from:
Arch 1
Muscles of facial expression are derived from:
Arch 2
Stylopharyngeus is derived from:
Arch 3
Pharyngeal constrictors are derived from:
Arch 4
Intrinsic laryngeal muscles are derived from:
Arch 6
Which nerves are derived from the pharyngeal arches?
5, 7, 9, 10
Vomer is derived from:
Arch 1
Palatine bone is derived from:
Arch 1
Lesser horn and upper portion of the body of the hyoid are derived from:
Arch 2
Greater horn and lower portion of body of hyoid bone are derived from:
Arch 3
Stapedius is derived from:
Arch 2
Anterior ligament of the malleus is derived from:
Arch 1
Sphenomandibular ligament is derived from:
Arch 1
What facial structures are formed from the mandibular process?
Lower lip, lower face, lower cheek regions, chin, mandible, body of the tongue
Maxillary processes form:
midface, upper cheek regions, upper lip sides, secondary palate, maxilla, zygomatic bone,
Growth factors ultimately activate:
transcription factors, which influence cellular responses such as proliferation, differentiation, apoptosis
Growth factors can act through ____ action
autocrine, paracrine, endocrine
Critical growth factor in craniofacial development
BMP
Functions of BMP
- Induction, formation, determination, migration of neural crest cells
- Patterning and formation of facial primordia
- Craniofacial skeletogenesis
- negative regulator of myogenesis (makes bone instead of muscle)
- regulator of early tooth morphogenesis and differentiation
___ BMP forms neuroectoderm
Low
___ BMP forms neural crest
High
Hox genes code for:
Transcription factors that make cells pattern into one tissue/organ type or another
During embryonic development, hox genes are involved in:
body segmentation
Hox is a ___ bp DNA sequence
180
Dlx genes control development of:
- ectodermal tissues derived from lateral border of the neural plate
- control patterning of branchial arch skeleton
Hox genes are not expressed in which arch?
Arch 1
____ regulate anterior-posterior identity
Hox genes
Rhombomeres
Segmented sections arising from either side of the neural tube
Removal of hox genes results in:
Everything defaulting to an arch 1 type pattern
Loss of hox expression in arch 2 causes:
loss of A-P identity; gives rise to duplicate arch 1 structures like duplicate malleus, incus, tympanic ring –> loss of stapes, styloid process, lateral horn of hyoid
What genes coordinate to place middle ear structures/primary jaw joint positioning?
Dlx, Hox
____ drives formation of incus
Dlx 1 and 2
What genes drives formation of malleus
Dlx 1, 2, 5, 6
___ tells the incus where to form in the AP axis
Hox
In the middle ear, no Hox a2 and Dlx 1/2 forms:
Incus
In the middle ear, no hox a2 and Dlx 1/2/5/6 forms:
Malleus
in the middle ear, Hox a2 and Dlx 1/2 forms:
stapes
In the development of the maxilla, ____ drives the formation of the maxilla and _____ forms the mandible
Dlx 1/2; Dlx 1/2/5/6
Treacher collins syndrome also known as:
congenital first arch syndrome
Treacher collins syndrome is caused by:
mutation in Treacle gene; failure of neural crest to properly migrate into the 1st arch –> deficient formation of various facial skeletal structures
True or false: cognitive function is abnormal with treacher collins
False - normal
(hearing defects very common though)
Pierre robin sequence
hypoplasia of the mandible, misplacement of tongue, cleft palate, defects of the eye and ear, airway obstruction
