CRANIOFACIAL DEVELOPMENT...

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CRANIOFACIAL DEVELOPMENT PRENATAL

dr.Indriati Dwi R, M.Kes Dep. Anatomi-Histologi

We cannot teach people anything; we can only help them discover it within themselves.

Galileo Galilei

– Production of egg and sperm

gametogenesis

– Transport gametes and fertilization

– Cleavage and Embryo transport

– implantation

– Formation of germ layers

– Establishment of the Basic Embryonic Body Plan

Embryonic stage (2 to 2)

1st week development

• Pregnancy dentocraniofacial development

• Early diagnosis clinical decision making

• Future : fetus in utero + potential patient

Contoh (populer) cranio/orofacial malformation:

• Cleft lip/palate

Transport of Gametes and Fertilization

• Ovulation :

– Mid point of menstrual cycle

– Under the influence LH and

FSH floats out of the ovary

• Oocyte transport

Before ovulation, fimbriae of the oviduct sweep over the ovary, and tube contract rhytmically. Oocyte is carried into the tube by motion of cilia on the epithelial lining.

Sperm transport

• Seminiferous tubules epididymis, biochem (environment condusive to independent motion)

• reflex ejaculation of semen (emission & ejaculation)

• Capasitation : A period conditioning in the female reprod tract.

Transport of Gametes and Fertilization Contd..

Fertilization :

• the process by which male and

female gametes fuse

• Occurs in the ampullary region of the oviduct

Transport of Gametes and Fertilization Contd..

VIABILITY OF GAMETES

• the oocyte cannot be fertilized after 24 hours and that it degenerates shortly thereafter .

• Most human sperms probably do not survive for more than 48 hours in the female genital tract

• Fertilization

• Development Before Birth

• Development of Male and Female Sex

• Birth

• Development After Birth

Fertilization

sperma vs ovum

(1)Sperm penetration of corona radiata

(2) Sperm binding and penetration of the

zona pellucida

(3) one sperm enters the egg Fuse zygote

The phase :

Acrosome reaction :

• Occurs after binding zona pellucida(zp)

• Release of enzymes (acrosin & trypsin like substance ) needed to penetrate zp.

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

zygote

embryoblast

• Fertilization

• Birth

Birth defects

Birth defects can be classified based on :

• severity, medical or social consequences,

• pathogenetic mechanism

• their clinical presentation

Classification based on severity

• Major anomalies: these are birth defects that have medical or social consequences for the affected child. Ex : cleft lip and palate, atrial septal defect, & radial aplasia

• Minor anomalies: birth defects that have no significant health or social implications for the affected child. Ex : partial syndactyly of the second and third toes. Multiple minor anomalies can provide clues to the diagnosis of multiple congenital anomaly syndromes and they may also be a marker for a chromosomal aberration

• Common variants : end of the spectrum of normal development rather than birth defects. Ex : fetal finger pads, sacral dimple

Classification based on pathogenesis

• Deformation : aberrant mechanical force distorting normally developing structures

• Disruption : destructive processes that alter a structure after it has formed normally

• Malformation : failure or inadequate completion of normal developmental processes.

• Dysplasia : abnormal cellular organisation or function within a specific tissue type throughout the body

Classification based on clinical presentation

• Single-system defects. Ex : cleft lip and palate, talipes, pyloric stenosis and congenital heart disease.

• Multiple-system defects. – Syndrome : consistently occur together

– Association : non-random fashion, have no common specific aetiology

– Sequence :

– Complex

• Fertilization

• Birth

Inner cell mass = embryo Outer cell mass = trophoblast

Pre-embyonic developmental stages

Cleavage

• Fertilization zygote 2 cell stage mitotic

divisionnumber of cells

Blastomeres

Cleavage is a series of mitotic division that

result in increase in cells, blastomere,

which become smaller with each division

Blastocyst Formation :

• At the time morula enter the uterine cavity,

fluids penetrate through zona pellucida into

intercellular spaces of inner cell mass(icm).

Single cavity (blastocele)

• Embryo =blastocyst

• Inner cell mass = embryo

• Outer cell mass = trophoblast

Cleavage

• Early pregnancy factor, an

immunosuppressant protein, is secreted by

the trophoblastic cells and appears in the

maternal serum within 24 to 48 hours after

fertilization

Heading to

Implantation

• Zona pellucida is covering the embryo until its reach uterus preparation for implantation

• Four to 5 days after fertilization, the zona pellucida is shed and the trophoblast adjacent to the embryoblast attaches to the endometrial epithelium.

Production of egg and sperm gametogenesis

Transport gametes and fertilization

Cleavage and Embryo transport

implantation

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

embryoblast

Implantation • = kontak fisik & fisiologis pertama;

antara blastocyst vs mucosa uterus (6th -8th day),

• 3 phase : –Preparation of the uterus for adhesion and

implantation

– Trophoblast-uterus adhesion

–Blastocyst movement into the uterus (mid portion of the posterior/anterior)

• Processes : zona pellucide disappear → polar

trophoblast touch the endometrium→secrete

proteolytase →dissolve the endometrium →

embedded into endometrium→coagulation plug

seal the space

Implantation

• Day by day of the conceptus

Week 2, days 8 – 14

Week 3 -8 [embryonic periode]

Month 3 to birth [fetus] : OOT

• The Placenta and Fetal Membranes

Week 2, days 8 – 14 Week 3 -8 [embryonic periode]

• Day 8

– The blastocyst embeded partially in endometrium

– Trophoblast has differentiated into 2 layer :

• Inner layer of mononucleated cellCytotrophoblast

• Outer layer of multinucl Syncytiotrophoblast

– Embryoblast also differentiated into 2 layer :

• An upper layer of cuboidal cells epiblast

• A lower layer of collumnar cells hypoblast

Day by day of the conceptus

Formation of Germ Layers and Early Tissue and Organ Differentiation: Third Week

Organogenetic Period: Fourth to Eighth Weeks

Trilaminar germ disc= endoderm + mesoderm

+ ectodermdetermination of head and tail

of germ disc

• endoderm: hypoblast cells are replaced by

epiblast cells

• ectoderm: epiblast changed the name into

ectoderm

• mesoderm: intraembryonic mesoderm

Formation of Trilaminar Germ Disc

[ Third week of development]

Formation of mesoderm: early of 3 weeks Gastrulation :

– primitive streak: cells of epiblast proliferate to form a

longitudinal arranged cell cord

– primitive groove

– primitive node

– primitive pit

• Head process (The notochordal process gives an

appearance of being a prolongation of the primitive

streak in the direction of the future head region of the

embryo) →notochordal tube → notochord :

– buccopharyngeal membrane

– cloacal membrane

Formation of Trilaminar Germ Disc

• The notochordal process immdiately rostral to the primitive

node and streak

• blood islands of the umbilical vesicle

Differentiation of trilaminar germ disc: 4th –

8th weeks

• differentiation: same cells which are

primordial and immature differentiate into

different cells which have specific structure

and function

• induction: some tissues effect the

differentiation, and determine the

differentiating orientation of another tissue

Fourth to eight week

4 to 8 week of development (organogenesis)

• Differentiation of ectoderm: CNS

• Differentiation of mesoderm: dermis,

bone, cartilage, CT, muscles, pleura,

peritoneum and pericardium, cardiovascular

and lymph system

• Differentiation of endoderm: digestive,

respiratory and urinary system

CRANIOFACIAL DEVELOPMENT

inside

Differentiation of ectoderm: from 18th –19th days

• neural plate: neuro-epithelium(neural ectoderm):

pseudostratified columnar epithel.

• neural fold

• neural groove

• neural tube: →CNS

/anterior neuropore: closed by 25th days

/posterior neuropore: closed by 27th days

• neural crest(mesoectoderm): two lines of cell

cords→ganglion

organogenesis

embryonic

Differentiation of mesoderm: 17th days

• paraxial mesoderm

– somite: 20th days, 3 pairs/per day, 42-44 pairs by the

end of 5th weeks

– sclerotome: →bone, cartilage

– myotome: →skeletal muscle

– dermatome: dermis and hypodermis

• Intermediate mesoderm:→kidney and

reproductive gland

– nephrotome: segmentation

– nephrogenic cord:

organogenesis

• lateral mesoderm:

– intraembryonic coelom: →body cavity

– somatic or parietal mesoderm: →muscle, CT,

parietal layer of pleura, peritoneum and

pericardium

– splanchnic or visceral mesoderm: →muscle, CT

of digestive tract, visceral layer of pleura,

peritoneum and pericardium

– mesenchyme: →cardiovascular and lymph

system

organogenesis

Differentiation of endoderm:

• primitive gut: →digestive, respiratory and

urinary system

organogenesis

• The Placenta and Fetal Membranes

components:

• The fetal part : formed by the villous chorion.

The chorionic villi that arise from it project into the

intervillous space containing maternal blood.

• The maternal part : formed by the decidua basalis

By the end of the fourth month, the decidua basalis is almost

entirely replaced by the fetal part of the placenta.

The placenta and fetal membranes perform the following

functions and activities: protection, nutrition, respiration,

excretion, and hormone production

The Placenta

Morphogenesis Embyonic developmental stages 2 to 2

• Bagian dari proses tumbuh kembang embryo

Fokus pada :

Cranio (kepala) - facial (wajah) - dental (gigi)

- calvaria

head formation

apparatus pharyngeal

palata

Odontogenesis

Other : tongue , salivary gland , sense organ

Head formation

• Occurs at the earliest stages

• Orofacial from CNC (ectoderm origin)

• Calvaria from mesoderm (paraxial)

• Brain : ~ brain development

Neural crest PHARYNGEAL APPARATUS

Neural crest Paraxial mesoderm

Lateral plate mesoderm

neurocranium (shaded

area) and the

viscerocranium ( black area). The bones of the neurocranium and viscerocranium are derived almost entirely from neural crest cells, except for the basilar part of the occipital bone (asterisk), which forms from mesoderm of the occipital sclerotomes, and the laryngeal cartilages (asterisk), which form from mesoderm within pharyngeal arches 4 and 6.

OSSIFICATION of the SKULL Neurocranium (basis cranii) • Endochondral

– os.occipital, os.sphenoid, os.ethmoid

• Intramembranous – Calvaria

Viscerocranium From neural crest • Endochondral

– Maleus, incus, stapes, proc.styloid os temporal – Os hyoid

• Intramembranous – Os temporal, os maxilla, os zygomaticum – Os mandibula

At 12 weeks showing the cartilaginous base of the cranium or chondrocranium formed by the fusion of various cartilages. D, At 20 weeks indicating the derivation of the bones of the fetal cranium.

head formation

apparatus pharyngeal

palata

odontogenesis

Other : tongue , salivary gland , sense organ

Pharyngeal apparatus • Very dominat, typical feature in head&neck dev; esp.

lateral and ventral regions of the head and neck.

• 4th week, by the mesoderm lateral plate & lateral extensions of the pharyngeal endoderm + CNC migration

• From ectoderm-mesoderm-endoderm. (Incl. CNC)

• Inti : jar.mesenchymal, diselubungi ectoderm di permukaan, dan lap.dalam dilapisi epithelia derivat endoderm

Tdd : • Pharyngeal arches :

5* • Pahryngeal

pouches : 4* • Pharingeal

grooves/cleft : 4 • [Pharyngeal

membrane] : 4

Pharyngeal arches

Pharyngeal pouches

Pharingeal grooves/cleft

[Pharyngeal membrane]

End of part ONE

CRANIOFACIAL DEVELOPMENT...

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