Tumbuh Kembang Oro-cranio-facial Prenatal

 Conceptus

Conceptus denotes the embryo and its adnexa (appendages or adjunct parts) or associated membranes

 Week 1, days 1-7 = pre-implantation  Week 2, days 8 – 14 = pre-embryonic  Week 3 -8 : [embryonic periode] Formation of Germ Layers and Early Tissue and Organ Differentiation: 3rd Week Organogenetic Period: 4th – 8th Weeks  Month 3 to birth [fetus]

Approximately 6 days after fertilization, the cell mass is termed a blastocyst.  IMPLANTATION Human chorionic gonadotropin now is produced in amounts that may be detected by commercial laboratories.

Week 2, days 8 – 14 • after implantation •  Formation of Bilaminar Germ Disc

3 germ layers2 first (endoderm and ectoderm)-> then 3 (mesoderm). The development of the 3rd germ layer is called gastrulation

Week 3= Early Tissue and Organ Differentiation • Trophoblast cells continue to invade uterine wall in the process of early placentation. Primary villi  2nd • Within the conceptus, gastrulation converts the bilaminar embryo into the trilaminar embryo • Formation of notochord

Epiblast cells migrate through the primitive streak. Mesoderm spreads between endoderm and ectoderm. Definitive (embryonic) endoderm cells displace the hypoblast.

During gastrulation, cells from the epiblast migrate and displace hypoblast cells to become definitive endoderm (which ultimately produces the future gut derivatives and gut linings) [1]. Meanwhile, the hypoblast and extraembryonic mesoderm eventually form the yolk sac [2].

is that epiblast is (biology) the outer layer of a blastula that, after gastrulation, becomes the ectoderm while hypoblast is (embryology) a type of tissue that forms from the inner cell mass and later is incorporated into the endoderm. Once the mesoderm has formed, the remaining epiblast cells cease to ingress and form the ectoderm.

Ectoderm→ Neural Tube→ baby= SSP→ badan spinal cord (medula spinalis) brain.

                Neural Crest→ orocraniofacial, PNS

Mesoderm → Visceral organ (dalam), notochord → axial skeleton

Neurulation the process by which the neural plate becomes the neural tube.dorsal surface of the embryonic disk -> lateral to the centre neural fold eventually meet each other and fuse. this begins in the middle and continues in the caudal and rostral direction -> complete by 4th week

the tips of the neural folds -> originate from the neural ectoderm. they are pinched off and move away migrating into the mesodermal part in between neural tube and neural ectoderm.

Embryonic folding is the process of converting the embryo from a flat disc, into a cylinder. This cylinder consists of three main layers, derived from the trilaminar embryonic disc: the endoderm in the center, the ectoderm on the outside, and the mesoderm, which is found between the two layers

Head Formation

Orofacial from CNC (ectoderm origin) → wajah

• most of teeth except for enamel and blood supply- skull bones (frontal, maxilla, mandible, nasal, zygomatic)

• Calvaria from mesoderm (paraxial) → The calvaria (skullcap) is made up of the superior portions of the frontal bone, occipital bone, and parietal bones.

Pharyngeal Arches

2.5 weeks there is invagination of surface epithelium lying between the cranial forebrain and the adjacent ventrally developing heart -> the heart eventually gets tucked into the ventral side while the brain grown anteriorly

3 weeks -> oropharyngeal membrane visible

Oropharyngeal membrane → Junction between oral ectoderm and foregut endoderm -> disintegrates in 4th week -> oral cavity becomes in contact with gut

Pharyngeal arches→ Begin to develop during the 4th week in utero• Give rise to significant number of structures the head and neck

• Pharyngeal arches separated on the external surface of the embryo by fissures called pharyngeal grooves or clefts• Pharyngeal pouches partially separates the arches on the internal aspect

The ectoderm-endoderm contact between each cleft and pouch → brancial membrane

Arches

• Pharyngeal arches separated on the external surface of the embryo by fissures called pharyngeal grooves or clefts• Pharyngeal pouches partially separates the arches on the internal aspect

The arches have nerve, blood, muscle

• Specific CN grows from the brain and invades each arch

• All structures including muscles, dermis, mucosa, arising from that arch are innervated by associated CN

• Arch 1 - Meckel's cartilage, important for growth of the mandible -

○ Middle ear bones - malleus and incus○ Perichondrium of cartilage forms sphenomandibular ligament

• Arch 2 - Reichert's cartilage - os hyoid

Arch 3 - cornu major

• Arch 4/6 - thyroid and cricoid cartilage

5→ regresi

• Meckel's cartilage occupies location that becomes the core of the mandibular corpus (body of the mandible) which forms around it• Bony mandible itself develops independently, directly from the embryonic CT that surrounds the cartilage

The muscles of mastication:-Anterior belly of digastric-Mylohyoid-Masseter-Tensor veli palatine-Tensor tympani

-Trigeminal-Innervates: face, teeth and mucosa of oral cavity + ant. 2/3 of tongue + muscles of mastication (mandibular division).Mandibular division (V1) grows into the main portion of arch 1, which is the mandibular process. The maxillary division (V2) supplies the maxillary process of arch 1.

Reichert's cartilage

-Muscles of facial expression-Stylohyoid-Stapedius-Post. belly digastric-Auricular muscles

-Stapes-Styloid process of the cranium-Stylohyoid ligament-Lesser horn of the hyoid bone-A portion of the hyoid body

The greater horn of the hyoid bone and part of the body

Stylopharyngeus

The cricothyroid and pharyngeal constrictor muscles

-The intrinsic laryngeal muscles-Innervated by the recurrent laryngeal branch of the Vagus

Grooves/ Cleft

Exterior ear canal.

Middle ear cavity.

3rd and 4th clefts are buried by the 2nd arch which grows over the 3rd and 4th arches.

The maxillary and lateral nasal processes

By merging of the two streams of ectomesenchyme of the mandibular processes

• The upper lip formed by the two medial nasal prominences and the two maxillary prominences.
• Lower lip and jaw form from the mandibular prominence that merge across the midline. Initially the maxillary and lateral nasal prominences are separated by a deep furrow, the nasolacrimal groove. Ectoderm in the floor of this groove forms a solid epithelial cord that detaches from the overlying ectoderm.

Pouches

1 = Middle ear cavity.

2= Palatine tonsil

3=inferiorparathyroid gland. thymus

4= superior parathyroid gland ultimobranchial body

Faces

4th-8th week

CNC : the major source of connective tissuecomponents, including cartilage, bone, andligaments in the facial and oral regions.

myoblasts, originating from paraxial andprechordal mesoderm, contribute to thecraniofacial voluntary muscles.

Growth Pattern:

The first and general component—accounting for most variation—is allometric – Brain growth predominates – flattening the cranial base – the displacement of the nasomaxillary segment; – growth of the orbital contents • The second component is alveolar remodeling – depends on the presence of tooth buds or teeth • The third component is mandibular condylar growth

5th week invagination fo the placode -> nostrils are visible (medial and lateral processes) -> laterally are the lateral nasal processes and beside them are the maxillary processes (visible at 6 weeks) -> by the 7th week they are fused forming the upper lip. These three prominences on the child's developing face grow towards the center of the face and fuse together during the 6th to 13th weeks of pregnancy. When this happens correctly, the child's lips, mouth, and palate develop normally.

migration CNCC (dorsal to ventral) eventually giving rise to max and mand bones

[end 3rd week] : stomodeum (calon oral&nasal cavities)

Berupa depresi ectoderm di bag.cephalic kontak dg endoderm = buccopharyngeal membrane (BPM)/oropharygeal membrane • BPM akan jd lokasi tonsila, memisahkanstomodeum dg foregut

[4th week]: bpm ruptur  komunikasi stomodeum-GIT primitif • Note : before that: pbentukan hipofise anterior dr stomodeum ectoderm, b’evaginasi di atap mulut primitif (depan bpm). Jalur : rathke’s pouche • Terbentuk tonjolan2 sekitar stomodeum; = facial prominences (t.u CNC & arcus pharynx I*)

Prominence → Becomes

1. Frontonasal → Forehead, bridge of nose, medial and lateral prominence
2. Maxilarry→ Cheeks, lateral portion of lip
3. M. nasal→ philtrum, crest and tip of nose
4. L. nasal→ alas of nose
5. Mandibular → lower lip

Palates

6th week

• Merging of two medial nasal processes results in the formation of the maxilla carrying the incisor teeth and primary palate and part of the lip• The medial nasal prominences move towards each other, fuse in the midline and form intermaxillary segment

Intermaxillary segment is the origin of the philtrum of upper lip, four max incisor teeth and alveolar process, primary palate

• At 7 weeks the palatine shelves forming from the maxillary processes are directed downward on each side of the developing tongue

• At 8 weeks the tongue has been depressed and the palatine shelves are elevated but not fused• Fusion of the shelves and nasal septum is completed, thus separating primitive OC into nasal and oral cavities

Two lateral palatal shelves and primary palate

→ cleft palate

Tongue

1 & 3

first branchial arches form the lateral lingual swellings on each side. foramen cecum is at the junction b/w anterior 2/3 and posterior 1/3.lateral lingual swellings grow and meet at the hypo pharyngeal eminence from arch 3

Salivary Gland

6th week

The connective tissue in the glands is derived fromneural crest cells. • All parenchymal (secretory) tissue arises byproliferation of the oral epithelium.

from buds that arise from the oral ectodermal lining near the angles of the stomodeum

from endodermal buds in the floor of the stomodeum

From multiple endodermal epithelial buds in the paralingual sulcus

Moleculat Regulation

The fate of cells is regulated by signalling molecules.

Growth factor and transcription

Penulangan

Endochondral ossification : tulang rawan mengalami transformasi menjadi tulang, dan sekelompok tulang muncul dari lautan jaringan tulang rawan. Terjadi pada condylus mandibula

Intramembranous ossification : tulang terjadi dari sekresi matrik tulang langsung dari jaringan ikat, tanpa terlebih dahulu membentuk tulang rawan. Terjadi pada cranial vault, maksila dan mandibula