Pharyngeal arches
Tongue and Salivary glands development
Face development
and defects
(face, jaws, palates, nose)
5. 5. 2022
Jan Křivánek
Body segmentation
Body segmentation
Body segmentation – is a human body segmented?
The same segmentation pattern as in a primitive species
The same signalling pathways
We are the result of minor changes in signalling
pathways and its final tuning
Face development – Neural crest
Doc. Petr Vaňhara
Neuralcrest
https://www.youtube.com/watch?v=1zpV5rzWXMA&ab_channel=GetAnimatedMedical
Development from zygote
https://www.youtube.com/watch?v=FhhWG3XzARY&ab_channel=FacultyofDentistry%2CUniversityofToronto
Face development
https://www.youtube.com/watch?v=iLbqzTlZ6yA&ab_channel=Osmosis
Pharyngeal arches
https://www.youtube.com/watch?v=oP1-ejJdZyc
Pharyngeal arches
Phylogenetically conserved organ, serves as a carrier for gills (which work as a respiratory organ)
First appears in sharks, around the pharyngeal gut
In vertebrates, transforms and forms the basis of important organs - branchiogenic organs
Wiki
The pharyngeal apparatus starts to develop in human embryos in the neck region behind the frontal (frontonasal)
prominence in the second half of the 4th week
Pharyngeal arches 6
Pharyngeal pouches (entodermal) 5
Pharyngeal clefts (grooves) (ectodermal) 4
Membranae obturantes 4
All structures are paired
Pharyngeal arches
Pharyngeal (branchial) arches (6)
The first four - cause a obvious segmented structure of the neck (5th
and 6th are rudimentary)
Cells of the mesencephalic and rhombencephalic part of neural crest
migrate into the paraaxial mesoderm of the first cervical somites and
contribute to formation on arches and subsequently organs
The formation of pharyngeal arches is controlled by the endoderm of
the pharyngeal arches
Ectomesenchymal derivatives: ligaments, cartilages, bones
Paraaxial mesoderm derivatives: muscles of pharyngeal arches and
branchial arteries
Migration of neural crest (ectomesenchyme) in several
migratory pathways
Controled by Hox genes which regulate expression of
transcription factors with effectory function
Pharyngeal pouches - 5
The first starts to develop on the stage of 5 somites
The 5th is rudimentary and develops as a part of the fourth pouch at end of the 1st month
Endodermal origin
Pharyngeal clefts - 4
They have the form of shallow grooves
ectoderm origin
Membranae obturantes - 4
Two-layer memranes that separate each ectoderm and entoderm groove (physiologically do not perforate in humans)
Frontal section through apparatus and branchial arch components
In each arch is: Cartilage
Skeletal muscle basis (mezoderm)
Arch artery
Branchial arch nerve
1. Pharyngeal arch (mandibular)
arch cartilage (Meckel´s cartilage) - malleus, incus, lig. mallei ant., sphenomandibulare lig.
muscles of mastication, mylohyoid and anterior belly of digastric, tensor tympani, tensor veli palatini
the 1st aortic arch - disappears (a small portion may persist and form maxillary artery)
the 1st branchial nerve - trigeminal
Derivatives of
pharyngeal
arches
2. Pharyngeal arch (hyoid):
arch cartilage (Reichert´s cartilage) - stapes, styloid process, lesser cornu of hyoid, upper part of body of the hyoid bone
muscles of facial expressions, stapedial and stylohyoid muscle, posterior belly of digastric
the 2nd aortic arch - disappears (small portions of this arch contributes to the hyoid and stapedial arteries)
the 2nd branchial nerve - facial
Derivatives of
pharyngeal
arches
3. Pharyngeal arch
arch cartilage - greater cornu of hyoid, lower part of body of the
hyoid cartilage
stylopharyngeus muscle
the 3rd aortic arch - has the same fate on the right and left sides
and forms the first part
of the internal carotid artery
the 3rd branchial nerve - glossopharyngeal
4. - 6. Pharyngeal arch
arch cartilages - laryngeal cartilages and tracheal rings
cricothyroid, levator veli palatini, constrictors of pharynx, intrinsic muscle of
larynx
the 4th aortic arch - gives rise on left: a part of the aortic arch between left
common carotid a left subclavian arteries; on the right: the proximal segment
of the subclavian artery
the 5th aortic arch - transient and obliterates
the 6th aortic arch - transformed into the pulmonary artery (their branches)
branchial nerves - vagus nerve /superior laryngeal, branch of vagus (from the 4th),
recurrent laryngeal branch of vagus (from the 6th)
Derivatives of
pharyngeal
arches
Transformation of cartilages of pharyngeal arches
(summary)
the 1st aortic arch – disappears (a small portion can persist to form short piece of the maxillary artery)
the 2nd aortic arch – disappears (small portions of this arch contributes to the hyoid and stapedial arteries)
the 3rd aortic arch – has the same development on the right and left side, it gives rise to the initial portion of the
internal carotid artery
(the continuation of its trunk is formed by the cranial portion of the dorsal aorta + primitive internal carotid)
the external carotid derives from
the cranial portion of the ventral aorta
the common carotid corresponds to a
portion of the ventral aorta between
exits of the third and fourth arches
Transformations of aortic arches (summary)
the 4th aortic arch - has ultimate fate different on the right and left side:
Left: forms part of the arch of the aorta between left common carotid and left subclavian artery
Right: forms the proximal segment of the right subclavian artery
the 5th aortic arch - is transient and soon obliterates
the 6th aortic arch - pulmonary arch - the proximal part transforms into the right branch of the pulmonary artery and
the distal part disappears
On the left side, the distal part persists as the ductus arteriosus during intrauterine life
The proximal part gives rise to the left branch of the pulmonary artery
Summary
Functional future has only the
1. pouch
2. - 4. obliterates and form a
sinus cervicalis
Pharyngeal clefts (ectodermal)
Derivatives of pharyngeal pouches 1. Cavum tympani and Eustachian tube
2. Fossa tonsilaris
3. Epithelial reticulum of thymus and gl. parathyr. inf.
4. gl. parathyroidea sup. + ultimobranchial body
5. rudimentary
Defects caused by maldifferentiation of the pharyngeal
apparatus
1. Branchial (cervical) cysts
2. Branchial (cervical) fistulae
3. Branchial (cervical) vestiges (rudiments of branchial arches)
4. Preauricular cysts a fistulae
5. Syndrome of the 1. branchial arch
6. DiGeorge syndrome
7. Ectopia of thymus
Branchial cysts (lateral neck cysts)
Origin from persisting sinus cervicalis, positioned under angulus mandibulae
Subcutaneously or deep around the pharynx (possibly larynx)
When a cyst ruptures, communication occurs with the body surface or pharynx
Lined with stratified squamous epithelium
They may contain a liquid content with cholesterol crystals
Usually clinically not important
https://subent.com/removal-of-branchial-cleft-cyst
Abnormal communication of the pharyngeal cavity with the body surface
They arise when the membranae obturantes obliterate
Between 2. pouch and cleft
(fossa tonsillaris - sternocleidomatoideus muscle)
Between 3. pouch and cleft
(tongue - art. sternoclavicularis)
Complete
at the outlet on the skin
Incomplete
external, internal
Branchial fistula (lateral cervical fistula)
Koltsidopoulos et Skoulakis, CMAJ, 2018
Small grooves, pits or cysts in skin
in triangular area anteriorly to the
pinna (auricle)
Origin: by persistence of sulci
separating auricular hillocks
Residues of some components of the pharyngeal arches, usually cartilage.
Occurrence: in the subcutaneous ligament of the neck above the lower 1/3 m.sternocleidomastoid
Rare
Branchial vestiges (rudiments of branchial arches)
Preauricular cysts and fistulae
Isaacson, IJPO, 2019
Complex malformation of the skeleton of the face (both jaws, palate), eye and ear, caused by delay or non-migration of
crista neuralis into the 1st pharyngeal arch
Types:
1) Treacher-Collins syndrome - dysostosis mandibulofacialis – autosomal dominant hereditary malformation
anatomically: hypoplasia to aplasia of zygomatic bones, hypoplasia of the upper and lower jaw, macrostomy, gothic
floor, hypoplastic and sparse teeth, malocclusion - the face shows a characteristic physiognomy
The First pharyngeal arch syndrome
2) Pierre-Robin syndrom
Hypoplasia of the mandible, gothic floor or posterior cleft palate, glossoptosis, ear defects
Autosomal recessive inheritance, X chromosome - linked
The intellect of individuals is not affected
Symptoms: due to the shortened base of the oral cavity, individuals after birth have difficulty feeding and breathing
(stridor - caused by a disproportion between the lower jaw and the tongue)
Resnick et at, 2019
Agnathia
Incorrect development of the 1st pharyngeal arch. Caused by improper migration of neural crest cells.
Anatomically: hypoplasia of the mandible, shortened philtrum - nasal hypoplasia, congenital aplasia of the thymus and
parathyroid glands, hypoplasia of the thyroid gland, defects of the heart and large vessels (right aortic arch), external
ear defects
Clinically: hypoparathyroidism (hypocalcemic seizures), absence of cellular immunity, manifestations of heart defect
Incidence 1: 50 000
Etiology: Most frequently deletion on chromosome 22 - (22q11)
DiGeorge syndrome
Thymus ectopia
Ectopia = correctly developer organ/structure in
incorrect place
When thymus fails to descent: Cervical thymus - near
the lower pair of parathyroid glands
Accessory thymus
The development of the tongue begins in the 5th week at the interface of the stomodeum and the beginning of the primitive pharynx
Anterior 2/3 of the tongue Apex and corpus linguae Formed from the mandibular process of the 1st pharyngeal arch
Posterior 1/3 of the tongue Radix linguae Formed from the 3rd and 4th pharyngeal arch
Apex and corpus
On the mandibular prominence are 3 mesenchymal protrusions covered with ectoderm:
Paired tuberculum linguale laterale (dx et sin) - distal lingual protrusion
Middle unpaired tuberculum impar (tuberculum linguale mediale) - middle tongue protrusion - more caudally
Tongue development
Radix linguae
2 foundations: copula - fused ectomezenchyme of the ventral ends of the hyoid arch
eminentia hypobranchialis - formed by fusion of ventral ends of 3rd and 4th pharyngeal arch
both the copula and the hypobranchial eminence are covered by the endoderm
Endoderm between the tuberculum impar and the dome very intensively proliferates and grows caudally, its luminization creates a
ductus thyreoglossus (see thyroid gland)
During the 6th week, the protrusions begin to fuse together
Lateral protrusions enwrap the unpaired tuberculum impar - a uniform apex and corpus linguae is formed
In definitive proportions, it resembles the original symmetrical origin of the tip and body of the tongue sulcus medianus linguae
(+septum linguae)
Only a small part of the body near the root of the tongue comes from the tuberculum impar)
The hypobranchial process merges with copula and
moves forward - approaching the base of the
corpus with which it merges
Radix - Pharyngeal part of the tongue
The fusion line is visible until
adulthood as a shallow "V" - shaped
groove - Sulcus terminalis
At the top of the "V" is a short channel:
Foramen caecum, remnant of the
proximal end of the ductus
thyreoglossus
The ectoderm and entoderm of the common base of the tongue differentiate into stratified squamous epithelium, taste bud cells, and
secretory compartments and ducts of the tongue glands
From ectomezenchyme of fused protrusions, the ligament of the tongue, blood and lymph vessels develop, incl. lymphatic tissue of
the root of the tongue
Muscles of the tongue come from the occipital myotoms, which move to its base and merge together.
During the fusion of myotomes, their motor nerves also merge (segmental arrangement) - the hypoglossus nerve is formed
Development of tongue papillae - in the 8th week – firstly papillae vallatae, foliatae (near the branches of the n. IX.), fungiformes
(branches of the n. Lingualis), filiformes (the 11th-12th week)
Taste buds - weeks 11-13
Sensitive innervation: Apex and corpus - trigeminal nerve (n. mandibularis)
Radix - n. Glossopharyngeus
Innervation of taste buds:
- Taste buds in papillae fungiformes fungal - n. facialis - chorda tympani
- Taste buds in papillae foliatae and circumvallatae - n. glossopharyngeus
- Taste buds in another location (radix lingue, isthmus faucium) - n. vagus
Tongue development
At birth: the tongue occupies the oral cavity
Postnatally: the root of the tongue descends into the pharynx – process finished at the 4th year of life
Ankyloglossia (lingua accreta) - short frenulum, limited mobility of the tip of the tongue, it is not possible to stick out the tongue
(difficulty breastfeeding), 1: 300 births. The frenulum usually lengthens spontaneously (surgery is not needed)
Congenital lingual cysts and fistulas - persistence of ductus thyreoglossus – clinically usually non important, causes problems only
when enlarged (discomfort in the pharynx or dysphagia)
Macroglossia - a rare, abnormally large tongue (associated with some syndromes, e.g. Down sy.)
Microglossia - a rare, abnormally small tongue (mostly associated with micrognathia; microglossia in combination with limb defects Hanhart's
syndrome)
Glossoptosis - displacement of the tongue dorsally. Pushes on the epiglottis, narrowing of the pharynx.
Lingua bifida (lingua fissa, glossoschisis) - a very rare anomaly, incomplete fusion of the tubercula lingualia lateralia
complete cleft - including the tip of the tongue (associated with the cleft of the lower lip and jaw)
partial cleft - deep longitudinal groove (groove) in the body of the tongue
Aglossia – tongue not developed
Overview of tongue development defects
Salivary glands as derivatives of the lining of the stomodea or other structures: the oral side of the palate, the tip
(ectoderm) and the root of tongue and the oral base (entoderm)
ectoderm: small salivary glands of lips and face, palate, gl. apicis lingue and parotid gland
entoderm: Weber's and Ebner's glands of the tongue, gl. submandibularis and gl. sublingualis
They all develop in a similar way:
From the epithelium (ecto- or entoderm) at the site of the future gland(s): cells begin to proliferate against
adjacent ectomezenchyme
They lengthen and branch - the basis for the glandular duct system is created, the last 6th generation form terminal
branches
Development of salivary glands
At the ends of the terminal branches (6th-7th generation) clusters of small spherical clusters of cells are subsequently
formed - singular acins
The secretion starts during the 5th month of development, followed by gradual lumen formation during the 6th month
of development
During this period, the division of the parenchyma into lobules begins, and thin septa are formed in glandular
parenchyma from the superficial mesenchyme.
Lobulization continues until birth when glands become fully functional and begin to excrete saliva
Basis for gl. parotis 4th - 6th week, at the upper edge of both corners of the mouth; after narrowing
of the rima oris, the ductus parotideus opens into the vestibule on the buccal side
Basis for gl. submandibularis 6th week
Basis for gl. sublingualis 8th week
Small salivary glands during 3rd month of development
Development of salivary glands
Face development
and defects
• 5 mm embryo appears as Carnegie
Stage 13 from ectopic pregnancy.
• Week 4-5, 26 - 30 days, 3 - 5 mm,
Somite Number 21 - 29
• Ectoderm: Neural tube continues to
close, Caudal neuropore closes,
forebrain
• Mesoderm: continued segmentation
of paraxial mesoderm (21 - 29
somite pairs), heart prominence
• Head: 1st, 2nd and 3rd pharyngeal
arch, forebrain, site of lens placode,
site of otic placode, stomodeum
• Body: heart, liver, umbilical, early
upper limb bulge
By the end of 1st month, the embryo has a form of short tube C-shaped curved dorsal side of embryo is convex and adjacent to
amnion, cephalic end of the embryo is more advanced in development than caudal one
Body parts: head, neck, body and tail
Length of the embryo is 8 -10 mm
Frontal prominence with prosencephalon
Mesencephalic prominence with mesencephalon - flexura cephalica
Occipital prominence with rhombencephalon - flexura occipitalis
Human fetus at the end of 1st month of development
Pharyngeal (branchial) aparatus:
6 Branchial arches
4 Branchial clefts (grooves) (ectodermal)
5 Branchial pouches (entodermal) Separated by membranae obturantes
Human fetus at the end of 1st month of development
1. Pharyngeal arch (mandibular) is divided into :
- Processus maxillaris
- Processus mandibularis
Branchial aparatus
Doc. Petr Vaňhara
By the end of 4th week of development the face development is initiated around the primitive mouth opening: stomodeum
The oral cavity develops from the stomodeum or primitive mouth
Bottom of the stomodeum is constituted by oropharyngeal membrane (membrana oropharyngea)
Development is organized by 2 centers:
- Prosencephalic
- Rhombencephalic
5 processes limit the stomodeum:
- Frontonasal prominence
- Paired maxillary prominences (processus maxillares)
- Paired mandibular prominences (processus mandibulares)
The base of the prominences is formed by an ectomesenchyme, which populated them from the lower mesencephalic and
upper rhombencephalic section of the neural crest.
The surface of the prominences is covered by an ectoderm, which also lines the stomodeum.
Prominences are initially separated from each other by deep grooves. It is a dynamic process - it starts at the end of the 4th
and beginning of 5th week of development and ends at about the 8th week. It depends on the proliferation of the
ectoderm and ectomezenchyme of the prominences and their further divisions, movements and different growth rates.
It is terminated by the fusion of the protrusions.
Face development
Face development
Doc. Petr Vaňhara
Initiation
Frontonasal prominence
(processus frontonasalis)
Paired prominences for upper jaw
(processus maxillares)
Paired prominences for lower jaw
(processus mandibulares)
Face development
Face development
processus maxillares
processus mandibularis
nasal placode
stomodeum
2. Pharyngeal arch
processus frontonasalis
stomodeum
Doc. Petr Vaňhara
Face development
Doc. Petr Vaňhara
Face development 4th week
Doc. Petr Vaňhara
• Nasal pits surrrounded by paired prominences – medial and lateral nasal prominence
• Area triangularis (nose)
• Intermaxilary segment (medial part of upper lip, part of upper jaw, primary palate)
Face development
Doc. Petr Vaňhara
Frontonasal prominence (gives rise to forehead, nose and middle part of upper lip - philtrum)
After the formation of nasal pits the ectomesenchyme is divided into parts:
Processus nasalis medialis
Processus nasalis lateralis
Triangular area between medial nose processes is called area triangularis
By the end of the 5th week, the medial nasal prominences fuse with
each other to form the intermaxillary segment
The segment proliferates caudally and inserts between ends of
maxillary prominences which merge with it during the 6th week
The intermaxillary segment gives rise to:
a) middle portion of the upper lip, or philtrum
b) the premaxillary part of the maxilla
c) the primary palate
At first, lateral nasal prominences are separated from the maxillary
prominences by a furrow, called the nasolacrimal groove
During next days, the maxillary prominences enlarge and fuse with
lateral nasal prominences.
Intermaxillary segment
Face development
Maxillary prominences fuse with:
1. Intermaxillar segment (formation of upper lip and palate)
2. Lateral nasal prominences (the rest of upper lip and part of nose)
Lateral nasal prominences are divided from the maxillary prominences by - sulcus nasolacrimalis
Doc. Petr Vaňhara
7th week
Face development
Doc. Petr Vaňhara
Summary of face development timing
Between 5. - 7. week
Beginning of 5th week: fusion of medial edges of mandibular
prominences: lower lip and chin
Beginning of 6th week: fusion of medial edges of maxillary
prominences with intermaxillary segment: upper lip
In the middle of 7th week: processus nasalis lateralis (at both
sides) fuse with the upper part of maxillary prominence
Between 7th-8th week: the fusion of maxillary and mandibular
processes: narrowing of rima oris
Doc. Petr Vaňhara
Face development - summary
Normal
Cyclopamine (teratogen)
anti-SHH Ab
Face development
Doc. Petr Vaňhara
Orofacial clefts
Clefts of the upper lip
Median clefts of the lower lip and chin (mandible)
Oblique facial clefts
Lateral, or transverse, facial clefts
Clefts emerge when the development of prominences was
incorrect: prominences did not fuse, were not established,
belated migration or proliferation
Facial clefts belong to the most common defects
Incidence: 1,7 : 1 000 newborns
Lateral or medial
Lateral:
• Unilateral cleft lip - results from failure of maxillary prominence to merge with the lateral edge of intermaxillary
segment on the one side
• Bilateral cleft lip - results from failure of mesenchymal masses of both maxillary prominences to merge with lateral
edges of intermaxillary segment
cheiloschisis unilateralis / cheiloschisis bilateralis
Clefts of the upper lip - cheiloschisis superior
Bilateral clefts of the lip and maxilla are very hard defect
Clefts can be uni and bilateral
The child can not suck and is in danger of aspiration of food
(Bi)lateral clefts of the lip and palate
Is caused by delay in development of intermaxillary segment due failure of the medial
nasal prominences (processus nasales mediales) to merge
Rarely with the cleft of apex nasi
Variable
Critical period: 27. - 35. day
The median cleft lip is one of symptoms of the Mohr syndrome
Median cleft lip (labium leporinum)
cheiloschisis mediana
Oblique facial cleft
(coloboma faciale, fissura orbitofacialis)
Uni- or bilateral, arises if the nasolacrimal groove us preserved
Combined always with the unilateral lip cleft and extends to the medial margin of the orbit
Results from failure of the mesenchymal masses of the maxillary prominences to merge with lateral and medial
nasal prominences
rare
Lateral/transverse facial cleft
fissura transversa faciei, macrostomia
Runs from the mouth toward the ear
Bilateral clefts results in a very large rima oris (macrostomia or „frog mouth“)
Results from failure of the lateral parts of the maxillary and mandibular prominences to merge
very rare
Median cleft of the lower lip and chin (mandible)
cheiloschisis et gnathoschisis inferior
Cleft resulting from failure of the mesenchymal masses of the mandibular prominences to merge completely with
each other
Always connected with cleft of the mandible and tongue
rare
Treatment: a comprehensive approach (cleft teams)
plastic surgeon, dentist - orthodontist, phoniatrist / anthropologist, event. psychologist
Oral cavity develops from the stomodeum or primitive mouth
5 processes limit the stomodeum:
frontonasal prominence
paired maxillary prominences (processus maxillares)
paired mandibular prominences (processus mandibulares) on sides
Stomodeum communicates with the body surface via primitive oral entrance
Bottom of the stomodeum - oropharyngeal membrane (membrana oropharyngea)
When the oropharyngeal membrane ruptures, the stomodeum becomes continuous
with the foregut
Roof of the stomodeum consists of a mesenchyme and ectoderm of the frontonasal
prominence
*
Development of oral cavity
membrana
oropharyngea
Begins at the 7th week
Completed by the end of the 12th week
The most critical period for the development of palate is from the beginning of 7th week to the beginning of 9th week
3 primordia:
Unpaired medial palate process and paired lateral palate processes (palatal shelves)
a) The medial palate process
Grows from the dorsal side of the intermaxillary segment at the end of the 5th week and gives rise to primary palate
Palatogenesis
b) Lateral palate processes - grow out from medial aspects of the maxillary prominences and give rise to the secondary palate
lateral palate processes are formed by mesenchyme, are covered by ectoderm a have shelf-like form (palatal shelves)
Palatal shelves initially grow in caudal direction and laterally along to primordium of the tongue later, due more rapid vertical growth
of mandibular processes the tongue descends caudally
Palatogenesis
During the 10th week shelves meet in the midline to finally fuse
The site of fusion of both lateral palate processes is known as
raphe palati
Palatogenesis
definitive palate originates by fusion of ventral edges of both lateral palatal shelves with the medial palate process
Line of fusion corresponds to the incisive canal (canalis incisivus)
The region of medial palate process (primary palate) and ventral parts of lateral palate processes undergo endesmal
ossification
The posterior portions of the lateral palate processes do not undergo ossification and give rise to the soft palate and
uvula
Palatogenesis
Hard palate
Primary
palate
Soft palate
Secondary
palate
Palatogenesis
• Primary palate (intermaxillary segment)
• Secondary palate (lateral maxillary plates)
Doc. Petr Vaňhara
Horizontalizace a srůst patrových ploténekPalatogenesis
Doc. Petr Vaňhara
Can be of isolated character or associated with clefts of the and upper lip
Complete or incomplete
unilateral or bilateral
The incidence of palate clefts is 1 : 2500 live births
Clefts of primary palate (C, D)
clefts of both primary and secondary palate (E)
clefts of secondary palate (F)
Palate clefts
Anteriorly to the incisive foramen
The primary and secondary palates are separated
Results from failure of fusion of lateral palatal shelves with the primary palate
Unilateral/bilateral
Clefts of primary palate (C,D)
Clefts of both primary and secondary palates (E)
Both anteriorly and posteriorly to the incisive foramen
Lateral palate processes are not fused and separated from the primary palate
The nasal septum is free
Usually associated with lateral cleft of the maxilla and upper lip cheilognathopalatoschisis
unilateralis / bilateralis (very serious malformation)
Posteriorly to the incisive foramen
Cause: lateral palatine processes do not fuse
Affect the all sections of palate (hard, soft and uvula staphyloschisis
/ uvula bifida)
Clefts of the secondary palate occur more frequently in females
than males (3:2)
Pierre-Robin syndrom: cleft of palate, hypoplasia of the lower jaw,
glossoptosis and pseudomacroglosia - malformation with
recessive inheritance bound to the X chromosom
Clefts of secondary palate (palatoschisis)
Staphyloschisis (uvula bifida) – rozštěp uvuly
Critical period in palatogenesis:
37. - 53. day (cleft of primary or both palates)
53. - 57/58. day (cleft of secondary palate)
Prediction of clefts (in general)
Healthy parents having child with cleft:
2% probability of the cleft of the second child
7% probability of the cleft (if both has cleft)
One parent had cleft and child with cleft is born
15% probablity of the cleft of the next child
Oral vestibule develops from the labiogingival
lamina (vestibular lamina)
Emerges during the 6th week
Thickened area of the ectoderm, fast proliferation
of ectoderm against mesenchymal core of
prominences that delineate the stomodeum
Cells in the center of lamina then undergo apoptosis
- labiogingival groove is established
Ventral section - the definitive lip
Dorsal section - the gingival ridge (torus)
Oral vestibule development
Maxilla
Paired bone, intramembranous ossification
Fusion of 3 parts:
Frontal part of the bone with incisors (intermaxilla) - intermaxillary segment
Lateral parts of the bone - both maxillary prominences (processus maxillares)
Lateral parts fuse to the frontal segment in incisive suture (sutura incisiva) on both sides
Ossification begins between 6 - 8 week
maxilla in newborns is shallow because has not formed alveolar processes yet (developed during the eruption of deciduos dentition)
Development of maxilla and mandible
Mandible
develops partly by intramembranous, partly by intracartilaginous ossification
Body of mandible and both ramus of mandible are of intramembranous origin (for ossification is used mesenchyme located
anterolateral to the Meckel cartilage that support the mandibular prominences
Ossification begins in the 6th week.
Condyle and coronoid process develop by intracartilaginous ossification (condyle between 12 - to 20 weeks, coronoid process yet later)
Lower jaw of neonates is low and its development continues in postnatal period
The angle between ramus and body of mandible continual reduces (from 140-150 to 120 for adult)
Development of maxilla and mandible
Nosal placodes → Nasal pits → Nasal sacs, grows
dorsocaudally to roof of stomodeum, from which are
initially separated by the oronasal membrane lens
Nasal cavity
Connection of nasal and oral cavities
During the 5th week the oronasal membrane perforates via openings - the primitive choanae and both nasal sacs
communicate to the stomodeum to form common mouth and nasal cavity (oronasal cavity, only for +-7 days) - see C
Sagittal sections through nasal pit and stomodeum:
Double-layered oronasal membrane (ectoderm of nasal cavity and stomodeum)
Lower part of intermaxillar segment – philtrum
Nose develops from 3 primordia simultaneously with development of face:
Middle and upper part of the intermaxillary segment - gives rise to the apex
Lateral nasal processes give rise to Dorsum et radix nasi, alae nasi
All primordia rapidly proliferate ventrally and nose protrudes (firstly flattened structure)
Nose development
Septum nasi - grows from the intermaxilary segment in form of vertical plate, which fuses
with lateral palate processes in the middle line (during 9-10th week)
At the time of development of the septum, bases of conchae develop on the lateral wall of
each nasal fossa (lower, middle and upper)
After 13 week, the ectoderm covering roof of both nasal fossae transforms in the olfactory
epithelium consisting of olfactory cells (unipolar neurons), whose axons constitute fila
olfactoria
The epithelium of sinuses is of the ectodermal origin
Nose development
Defects are of rare occurrence
Occur separated or in association with anomalies of the upper lip and jaw or
whole face
Aplasia (agenesis) of the nose - caused by lack of nasal placodes
Hypoplasia of the nose - a small nose with a single cavity
combined with micrognathy
Nasoschisis (nares bifides) - median cleft of the nose - caused by non-fused
medial nasal prominences
The extent of cleft is variable - from shallow groove on the nose apex to the
complete duplication of the nasal septum
Developmental defects of the nose
Atresia introitus nasi (vestibuli nasi) - vestibulum nasi is closed by thin funnel shaped membrane (caused of persistence
of epithelial plugs, which obturate nostrils of the fetus in the 3rd month)
Atresia choanarum – choana is closed with connective tissue membrane or bone plate
persistence of the oronasal (buconasal) membrane
1: 10 000
autosomal dominant inheritance
Other defects: nasus duplex (rhinodynia), proboscis
Veratrum californicum
http://www.sci-news.com/othersciences/anthropology/newborn-babies-skills-pick-out-individual-words-06863.html