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Pre natal dev  of face /certified fixed orthodontic courses by Indian dental academy
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Pre natal dev of face /certified fixed orthodontic courses by Indian dental academy

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The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and offering a wide range of dental certified courses in different formats.

Indian dental academy provides dental crown & Bridge,rotary endodontics,fixed orthodontics,
Dental implants courses.for details pls visit www.indiandentalacademy.com ,or call
0091-9248678078

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    Pre natal dev  of face /certified fixed orthodontic courses by Indian dental academy Pre natal dev of face /certified fixed orthodontic courses by Indian dental academy Presentation Transcript

    • www.indiandentalacademy.com INDIAN DENTAL ACADEMY Leader in continuing dental education www.indiandentalacademy.com
    • PRE –NATAL DEVELOPMENT OF FACEwww.indiandentalacademy.com
    • CONTENTS • INTRODUCTION. • REVIEW OF GENERAL EMBRYOLOGY. CELL CYCLE. REPRODUCTION OF CELLS. MITOSIS & MEIOSIS. GAMETOGENESIS. FERTILIZATION. • PRE – IMPLANTATION DEVELOPMENT. • POST – IMPLANTATION DEVELOPMENT. EMBRYONIC PERIOD (THE NEXT 7 WEEK). FETAL PERIOD (THE NEXT 7 CALENDAR MONTH). www.indiandentalacademy.com
    • • ORIGIN & MIGRATION OF NEURAL CREST CELLS. • PHARYNGEAL ARCHES & ITS DERIVATIVES. • PHARYNGEAL POUCHES & ITS DERIVATIVES. • ECTODERMAL CLEFTS & ITS DERIVATIVES. • FORMATION OF FACE. • MOLECULAR REGULATION OF FACIAL DEVELOPMENT. • DEVELOPMENT OF FACIAL SKELETON • CONCLUSION. • REFERENCES. www.indiandentalacademy.com
    • INTRODUCTION THE MOBILE MASK IN FRONT OF HUMAN BRAIN BEGAN TO ATTRACT OUR ATTENTION WHEN WE WERE BABIES AND CONTINUES TO FASCINATE US AS LONG AS WE LIVE W. K. GREGORY, OUR FACE FROM FISH TO MAN. www.indiandentalacademy.com
    • WITHIN THE TEXT OF THE CRANIOFACIAL EMBRYOLOGY,WE COME ACROSS TWO TERMS GROWTH & DEVELOPMENT. WHAT DOES THE TERM GROWTH IMPLIES TO US ? CHANGE IN MAGNITUDE. DOES IT EXPLAIN TO HOW FAR IT HAPPENS? WHY SHOULD IT HAPPEN IN A PREDETEMINED DIRECTION? www.indiandentalacademy.com
    • TO UNDERSTAND THIS ,THE MORE DESCRIPTIVE & EXPLANATORY TERM ,DEVELOPMENT IS ADDED. DEVELOPMENT CONNOTES A MATURATIONAL PROCESS INVOLVING PROGRESSIVE DIFFERENTATION AT THE CELLULAR & TISSUE LEVELS,THERE BY FOCUSING ON THE ACTUAL BIOLOGICAL MECHANISM THAT ACCOUNTS FOR OVERALL GROWTH. www.indiandentalacademy.com
    • • WHAT IS COMPOSITE EQUILIBRIUM? • IT IS A CHANGING MORPHOLOGIC EQUILIBRIUM, WHICH RECYCLES THROUGHOUT THE LIFE CYCLE OF AN INDIVIDUAL. • IS IT SO IMPORTANT FOR US TO KNOW THE PRE -NATAL DEVELOPMENT OF FACE. • HOW IS IT RELATED TO THE FIELD OF ORTHODONTICS ? www.indiandentalacademy.com
    • MAL-OCCLUSION OR OTHER DYSPLASIA (INCLUDING CONGENITAL MALFORMATIONS), ALTHOUGH CLINICALLY ABNORMAL,IS NONETHLESS IN A BALANCED STATE. CLINICAL TREATMENT CAN DISTURB THIS STATE OF STRUCTURAL & FUNCTIONAL EQUILIBRIUM,AND A NATURAL REBOUND CAN FOLLOW. TO KNOW THIS ,EACH OF US SHOULD KNOW HOW DEVELOPMENT OF FACE PROCCEDS WITHOUT ANY GREAT VARIATIONS. www.indiandentalacademy.com
    • CELL CYCLE • IS THAT PERIOD OF TIME BETWEEN THE BIRTH OF A CELL, AS A RESULT OF THE DIVISION OF ITS PARENT CELL, AND ITS OWN DIVISION TO PRODUCE TWO DAUGHTER CELLS. • IN EMBRYONIC CELLS IT LASTS FOR ABOUT 1-2hrs & IN ADULT CELLS LONGER THAN 12hrs. • THE CYCLE IS DIVIDED INTO 4 DISTINCT PHASES G1, S, G2 & M PHASE. • THE COMBINATION OF G1, S & G2 PHASES IS KNOWN AS INTERPHASE. www.indiandentalacademy.com
    • PHASES OF CELL CYCLE • G1 PHASE. DECIDES TO DIVIDE OR NOT. GENERATION OF METABOLITES. GO PHASE. INDUCTIVE INFLUENCE OF GROWTH FACTORS . ROLE OF ONCOGENES. • S PHASE REPLICATION OF DNA. • G2 PHASE BREAK DOWN OF NUCLEAR ENVELOPE. CHROMOSOME CONDENSATION. www.indiandentalacademy.com
    • • WHAT REGULATES THE TRANSITIONS BETWEEN THE CELL CYCLE PHASES ? • MAXIMUM ABUNDANCE OF CYCLINS IN THE CELL BETWEEN G1 & S PHASE, G2 & M PHASE. • ACTIVATION OF PROTEIN KINASE ENZYMES CALLED P34. • IDENTIFICATION OF TARGET PROTEINS. www.indiandentalacademy.com
    • REPRODUCTION OF CELLS • AS THE BODY GROWS IN SIZE MOST CELLS UNDER GO REPEATED DIVISION. • SOME CELLS LOSE THE ABILITY TO UDER GO DIVISION LIKE NEURONS,WHERE AS IN STEM CELLS IT MAY PERSIST, LIKE HAEMOPOETIC TISSUE OF BONE MARROW. • DURING EARLY EMBRYONIC LIFE, CONTROL APPEARS TO BE LOCAL INVOLVING,THE DIFFUSION OF METABOLITES. • AT LATER STAGES,ENDOCRINE CONTROL COMES INTO PLAY. www.indiandentalacademy.com
    • TYPES OF CELL DIVISION • MITOSIS OCCURS IN MOST SOMATIC CELLS. • MEIOSIS, OCCURS BEFORE FINAL PRODUCTION OF GAMETES. • NO OF CHROMOSOMES IS REDUCED TO HALF ,SO THAT AT FERTILIZATION THE DIPLOID NO IS RESTORED. • REASSORTMENT OF GENES, THE ESSENCE OF EVOLUTION. • MITOSIS & MEIOSIS DIFFERS CHIEFLY IN CHROMOSOMAL BEHAVIOUR. • IN MEIOSIS TWO DIVISIONS OCCUR IN QUICK SUCCESSION, UNLIKE MITOSIS (MEIOSIS I,HETEROTYPICAL DIVISION) LIKE MITOSIS (MEIOSIS II,HOMOTYPICAL DIVISION) www.indiandentalacademy.com
    • MITOSIS www.indiandentalacademy.com
    • MEIOSIS www.indiandentalacademy.com
    • GAMETO GENESIS • SEXUAL REPRODUCTION IS FOUND THROUGHOUT THE ANIMAL KINGDOM. • THE MALE GONAD OR TESTIS PRODUCES MANY SMALL MOTILE GAMETES OR SPERMATAZOA, WHICH CONSISTS OF HAPLOID NO OF CHROMOSOMES. • IN CONTRAST THE FEMALE GONAD OR OVARY PRODUCES FEWER, LARGER, NON MOTILE OVA (EGGS), WHICH ALSO CONSISTS OF HAPLOID NO OF CHROMOSOMES. www.indiandentalacademy.com
    • • APPEARANCE OF GERM CELLS IN THE WALL OF YOLK SAC. • MIGRATION OF THESE CELLS TO THE DEVELOPING GONADS. • GERM CELLS UNDERGO GAMETOGENESIS. MEIOSIS TO REDUCE THE NO OF CHROMOSOMES CYTODIFERENTATION OF THESE CELLS TO COMPLETE MATURATION. www.indiandentalacademy.com
    • OOGENESIS www.indiandentalacademy.com
    • • BY 5th MONTH OF PRENATAL DEVELOPMENT,THE TOTAL NO OF GERM CELLS IS ESTIMATED TO BE 7 MILLION. • AT THIS TIME CELL DEATH BEGINS. • ALL SURVIVING PRIMARY OOCYTES HAVE ENTERED THE 1ST MEIOTIC DIVISION. • PRIMARY OOCYTE ,TOGETHER WITH ITS SUUROUNDING FLAT EPITHELIAL CELLS,IS KNOWN AS A PRIMORDIAL FOLLICLE. www.indiandentalacademy.com
    • MATURATION OF OOCYTES • ROLE OF OOCYTE MATURATION INHIBITOR, SECRETED BY FOLLICULAR CELLS. • ON ONSET OF PUBERTY, PRIMORDIAL FOLLICLES BEGIN TO MATURE . • IN EACH OVARIAN CYCLE ,ONLY ONE FOLLICLE REACHES FULL MATURITY. www.indiandentalacademy.com
    • • CHANGE IN THE ORIENTATION OF THE FOLLICULAR CELLS FROM FLAT TO CUBOIDAL. • PROLIFEATION OF THESE CELLS TO PRODUCE A STRATIFIED EPITHELIUM OF GRANULOSA CELLS. • SECRETION OF GLYCOPROTEIN FROM GRANULOSA CELLS ON THE SURFACE OF THE OOCYTE FORMING THE ZONA PELLUCIDA. • THE FOLLICLE IS NOW KNOWN AS PRIMARY FOLLICLE www.indiandentalacademy.com
    • • APPEARANCE OF FLUID FILLED SPACES BETWEEN GRANULOSA CELLS. • COALESCENCE OF THESE SPACES FORMS THE ANTRUM FORMING THE SECONDARY FOLLICLE. • FORMATION OF CUMULUS OOPHORUS. • AT MATURITY THE FOLLICLE MAY BE 10 MM OR MORE IS KNOWN AS THE GRAAFIAN FOLLICLE. www.indiandentalacademy.com
    • SPERMATOGENESIS AT BIRTH GERM CELLS CAN BE RECOGNISED IN THE SEX CORDS OF THE TESTIS. APPEARANCE OF SUSTENTACULAR OR SERTOLI CELLS. SHORTLY BEFORE PUBERTY THE SEX CORDS ACQUIRE LUMEN & BECOME THE SEMINIFEROUS TUBULES. www.indiandentalacademy.com
    • PRIMORDIAL GERM CELLS SPERMATOGONIA TYPE A TYPE B www.indiandentalacademy.com
    • SPERMIOGENESIS • TRANSFORMATION OF SPERMATIDS INTO SPERMATOZOA. • THESE CHANGES INCLUDE, FORMATION OF THE ACROSOME. CONDENSATION OF THE NUCLEI. FORMATION OF NECK, MIDDLE PIECE,&TAIL. SHEDDING OF THE MOST OF THE CYTOPLASM. www.indiandentalacademy.com
    • UNION OF THE GAMETES • CHARACTERISED BY FUSION OF DISTINCT MALE & FEMALE GAMETES (SPERM & EGG RESPECTIVELY) PRODUCED BY DIFFERENT PARENTAL FORMS. • MAMMALIAN EGGS ARE FERTILIZED ,WHEN THEY ARE IN SECOND MEIOTIC METAPHASE. • UNION LEADS TO FERTILIZATION CAUSING THE CELL DIVISION CELL CYCLE TO RESUME. • HERE AFTER,CELL DIVISION (SEGMENTATION OR CLEAVAGE) PROCEEDS WITHIN THE ZONA PELLUCIDA TO BLASTOCYST STAGE. www.indiandentalacademy.com
    • • FERTILIZATION OF THE EGG OCCURS IN THE AMPULLARY REGION OF THE UTERINE. • SPERMATOZOA IS NOT ABLE TO FERTILIZE THE OOCYTE IMMEDIATELY UPON ARRIVAL IN THE FEMALE GENITAL TRACT BUT MUST UNDERGO, CAPACITATION. THE ACROSOME REACTION. www.indiandentalacademy.com
    • CAPACITATION • PERIOD OF CONDITIONING IN THE FEMALE REPRODUCTIVE TRACT. • EPITHELIAL INTERACTIONS BETWEEN THE SPERM & MUCOSAL SURFACE OF THE TUBE. • REMOVAL OF GLYCOPROTEIN COAT & SEMINAL PLASMA PROTEINS THAT OVERLIES THE ACROSOMAL REGION. • AFTER THIS ,SPERM CELLS CAN PASS THROUGH THE CORONA CELLS &UNDERGO ACROSOME REACTION. www.indiandentalacademy.com
    • ACROSOME REACTION DIVIDED INTO THREE PHASES, PHASE 1: PENETRATION OF CORONA RADIATA. PHASE 2: PENETRATION OF ZONA PELLUCIDA. PHASE 3: FUSION OF THE OOCYTE & SPERM CELL MENBRANES. www.indiandentalacademy.com
    • FERTILIZATION PATHWAY www.indiandentalacademy.com
    • REACTION OF THE EGG AFTER FERTILIZATION • CORTICAL & ZONA REACTIONS. • RESUMPTION OF THE SECOND MEIOTIC DIVISION. • METABOLIC ACTIVATION OF THE EGG. • INTIATION OF THE CLEAVAGE. www.indiandentalacademy.com
    • PRE - IMPLANTATION DEVELOPMENT (THE 1ST 7 DAYS) www.indiandentalacademy.com
    • • AFTER THE TWO CELL STAGE THE ZYGOTE UNDER GOES SERIES OF MITOTC DIVISIONS. • FORMATION OF BLASTOMERES. • UNTIL THE EIGHT CELL STAGE ,THEY FORM A LOOSELY ARRANGED CLUMP. www.indiandentalacademy.com
    • • COMPACTION OF CELLS ,WHICH ARE HELD TOGETHER BY TIGHT JUNCTIONS. • THIS PROCESS SEGREGATES INNER CELLS FROM OUTER CELLS. • APPROXIMATELY AFTER THREE DAYS OF FERTILIZATION COMPACTED CELLS DIVIDE TO FORM A 16 CELL MORULA . • INNER CELLS OF THE MORULA CONSTITUTE THE INNER CELL MASS & SURROUNDING CELLS COMPOSE THE OUTER CELL MASS. • INNER CELL MASS GIVES RISE TO EMBRYOBLAST & THE OUTER CELL MASS GIVES RISE TO TROPHOBLAST, WHICH LATER CONSTITUTES THE PLACENTA. www.indiandentalacademy.com
    • UNCOMPACTED CELLS COMPACTED CELLS www.indiandentalacademy.com
    • BLASTO CYST FORMATION • BY THE TIME MORULA ENTERS THE UTERINE CAVITY FLUID BEGINS TO PENETRATE THROUGH THE ZONA PELLUCIDA INTO THE INTER CELLULAR SPACES OF THE INNER CELL MASS. • THESE SPACES BECOME CONFLUENT TO FORM A SINGLE CAVITY ,THE BLASTOCELE. • AT THIS TIME EMBRYO IS A BLASTOCYST. www.indiandentalacademy.com
    • INNER CELL MASS ARE NOW CALLED THE EMBRYO BLAST &THOSE OF OUTER CELL MASS ARE CALLED TROPHOBLAST. ZONA PELLUCIDA NOW DISAPPEARS TO ALLOW IMPLANTATION TO BEGIN. ABOUT THE SIXTH DAY TROPHOBLASTIC CELLS OVER THE EMBRYOBLAST POLE BEGIN TO PENETRATE BETWEEN THE EPITHELIAL CELLS OF THE UTERINE MUCOSA. IMPLANTATION OF THE ZYGOTE TAKES PLACE AS A RESULT OF MUTUAL ACTION OF TROPHOBLASTIC & ENDOMETRIAL CELLS. www.indiandentalacademy.com
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    • SUMMARY OF EVENTS DURING THE 1ST WEEK OF DEVELOPMENT www.indiandentalacademy.com
    • POST – IMPLANTATION DEVELOPMENT www.indiandentalacademy.com
    • EMBRYONIC PERIOD (THE NEXT 7 WEEKS) • DIVIDED INTO THREE PERIODS • PRESOMITE (8 – 21 DAYS) FORMATION OF GERM LAYERS & FETAL MEMBRANES. • SOMITE (21 – 31 DAYS) FORMATION OF DORSAL METAMERIC SEGMENTS,BODY SYSTEMS & ORGANS. • POST SOMITE (32 – 56 DAYS) FORMATION OF BODYS EXTERNAL FEATURES. www.indiandentalacademy.com
    • PRESOMITE PERIOD (8 – 21 DAYS) • EMBRYONIC DISK IS COPMOSED OF TWO PRIMARY GERM LAYERS. • ECTO DERM. • ENDO DERM. www.indiandentalacademy.com
    • PRE CHORDAL PLATE • AT THE 14TH DAY THERE IS AN EARLY DEMARACTION AT THE ANT. POLE OF THE INTIALLY OVAL DISK. • AN ENDODERMAL THICKENING APPEARS IN THE FUTURE MID CEPHALIC REGION, THE PRE CHORDAL PLATE. PERFORMS HEAD ORGANIZING FUNCTION PREFACES THE DEVELOPMENT OF THE OROFACIAL REGION. www.indiandentalacademy.com
    • PRIMITINE STREAK • APPEARANCE OF THE THIRD PRIMARY GERM LAYER,THE MESODERM. • THE RESULTANT BULGE IN THE DISK IS GROOVED CRANIO CAUDALLY. • FROM THE PRIMITIVE STREAK THE RAPIDLY PROLIFERATING TISSUE KNOWN AS THE MESEN CHYME FORMS THE INTRA EMBRYONIC MESODERM. www.indiandentalacademy.com
    • • MIGRATION OF MESENCHYMAL CELLS. • BILAMINAR DISK IS CONVERTED INTO A TRILAMINAR STRUCTURE. • FORMATION OF THE NOTOCHORD BY THE PROLIFERATION & DIFFERENTATION OF THE CRANIAL END OF THE PRIMITIVE STREAK. www.indiandentalacademy.com
    • NOTOCHORD • TERMINATES ANTERIORLY AT THE PRE CHORDAL PLATE. • SERVES AS THE AXIAL SKELETON OF THE EMBRYO. INDUCES FORMATION OF THE NEURAL PLATE IN THE OVER LYING ECTODERM (NEURAL ECTODERM) LATERAL MESODERM WHICH INDUCES EPIDREMAL DEVELOPMENT(CUTANEOUS ECTODERM). www.indiandentalacademy.com
    • DERIVATIVES OF THE THREE PRIMARY GERM LAYERS • ECTODERM CUTANEOUS STRUCTURES & NEURAL SYSTEMS. • MESODERM CARDIOVASCULAR SYSTEM ,THE LOCOMOTOR SYSTEM, CONNECTIVE TISSUES & DENTAL PULP. • ENDODERM LINING EPITHELIUM OF THE RESPIRATORY TRACT & ALIMENTARY CANAL,SECRETORY CELLS OF THE LIVER &PANCREAS. www.indiandentalacademy.com
    • ABOUT 20 DAYS THE NEURAL PLATE ECTODERM UNDER GOES INFOLDINGS ALONG THE MIDLINE FORMING THE NEURAL FOLDS. INFOLDING OF THE NEURAL FOLDS CREATE NEURAL GROOVE. ABOUT 22 DAYS THE NEURAL FOLDS FUSE ,IN THE SITE OF THE FUTURE OCCIPITAL REGION. THIS INTIAL CLOSURE PROCEEDS BOTH CEPHALICALLY & CAUDALLY TO FORM THE NEURAL TUBE. THIS NEURAL TUBE IS SUBMERGED BENEATH THE SUPERFICIAL COVERING OF THE CUTANEOUS ECTODERM www.indiandentalacademy.com
    • THE SOMITE PERIOD (21 – 31 DAYS) • CHARACTERISED BY FOLDINGS & STUCTURING. • CONVERSION OF THE EMBRYONIC DISK INTO A TUBULAR STRUCTURE. • DEVELOPMENT OF THE BRAIN & SPINAL CORD FROM THE NEURAL PLATE. www.indiandentalacademy.com
    • DEVELOPMENT OF MESODERM INTO THREE AGGREGATIONS www.indiandentalacademy.com
    • ORGANIZATION OF PARAXIAL MESODERM INTO A NO OF SEGMENTS. EACH SOMITE DIFFERENTIATES INTOTHREE PARTS. SCLEROTOME DERMATOME MYOTOME SOMITE PERIOD IS CHARACTERIZIED BY ESTABLISHMENT OF MOST OF THE ORGAN SYSTEMS. www.indiandentalacademy.com
    • POST SOMITE PERIOD (32 -56 DAYS) • CHARACTERIZIED BY FADING OF THE PREDOMINANT SEGMENTED SOMITES. • HEAD DEVELOPMENT DOMINATES THIS PERIOD. • RECOGNITION OF FACIAL FEATURES. • EMBRYO AT THE END OF THIS PERIOD IS TERMED FETUS. www.indiandentalacademy.com
    • FETAL PERIOD (THE NEXT 7 CALENDAR MONTH) • RAPID GROWTH & REPROPORTIONING OF BODY COMPONENTS. • LITTLE FURTHER ORGANOGENESIS OR TISSUE DIFFERENTIATION. • BODY GROWS RAPIDLY AS COMPARED TO THE PRECOCIOUS GROWTH & DEVLOPMENT OF HE HEAD. • AT 4TH MONTH OF INTRA UTERINE LIFE THE FACE ASSUMES A HUMAN APPEARANCE. www.indiandentalacademy.com
    • ORIGIN & MIGRATIN OF NEURAL CREST CELLS www.indiandentalacademy.com
    • • UNDER THE INDUCTIVE INFLUENCE OF THE NOTOCHORD,THE NEURAL PLATES UNDERGO INFOLDING TO FORM THE NEURAL TUBE. • INFOLDING OF THE NEURAL TUBE FORMS NEURAL FOLDS FROM WHERE THESE SPECIAL GROUP OF CELLS ARISE. • FORMED FIRST IN THE ANGLE BETWEEN THE DEVELOPING NEURAL TUBE & THE ECTODERMAL SHEET THAT COVERS THE DORSUM OF THE EMBRYONIC DISC. • INTIAL MIGRATION OF THESE CELLS IS PROBABLY 19-38 DAYS AFTER FERTILIZATION. www.indiandentalacademy.com
    • • THESE CELLS MIGRATE THROUGH CELL FREE SPACES BENEATH THE SURFACE ECTODERM. • MIGRATION OF THESE CELLS IS NOT RANDOM, BUT FOLLOWS A DEFINITE PATTERN,BOTH SPATIALLY &TEMPORALLY. • WHAT GUIDES THESE CELLS ? DISRUPTION OF THE ECTODERMAL MEMBRANE. COMBINATION OF NEUROTROPHISM. CLEAVAGE PLANES. SUCCESION OF MICROENVIRONMENT. DIFFERENTIAL GROWTH OF CELLS. MORPHOGENIC TISSUE INTERACTION.www.indiandentalacademy.com
    • THE TWO PRINCIPAL SOURCES OF MESENCHYME IN HEAD ARE THE PARAXIAL MESODERM & THE NEURAL CREST CELLS. CEPHALIC NEURAL CREST CELLS ARE PARTICULARILY IMPORTANT IN THE FORMATION OF THE FACIAL PART OF THE SKULL. THESE CELLS MIGRATE BOTH IN FRONT & BEHIND THE DEVELOPING EYE TO REACH THE PREDETERMINED SITES FACIAL SWELLINGS. MIGRATION IS ASSITED BY HYALURONATE RICH FIBRONECTIN,COLLAGEN,CHONDRITIN SULFATE &GLYCOAMINOGLYCANS. THE DISTRIBUTION & CONCENTRAION OF THESE PRODUCTS VARIES ALONG THE MIGRATION ROUTE. www.indiandentalacademy.com
    • BREAK www.indiandentalacademy.com
    • • PHARYNGEAL ARCHES & ITS DERIVATIVES. • PHARYNGEAL POUCHES & ITS DERIVATIVES. • ECTODERMAL CLEFTS & ITS DERIVATIVES. • FORMATION OF FACE. • MOLECULAR REGULATION OF FACIAL DEVELOPMENT. • DEVELOPMENT OF FACIAL SKELETON • CONCLUSION. • REFERENCES. www.indiandentalacademy.com
    • PHARYNGEAL ARCHES www.indiandentalacademy.com
    • • APPEARS DURING THE 4th & 5th WEEK OF INTRA UTERINE DEVELOPMENT. • CONSISTS OF BARS OF MESENCHYMAL TISSUE SEPARATED BY DEEP CLEFTS KNOWN AS PHARYNGEAL (BRANCHIAL) CLEFTS. • ON DEVELOPMENT, A NO OF OUT POCKETING APPEARS, ALONG THE LATERAL WALLS OF THE PHARYNGEAL GUT WHICH ARE THE PHARYNGEAL POUCHES. • CONTRIBUTE NOT ONLY TO THE FORMATION OF THE NECK BUT ALSO PLAY AN IMPORTANT ROLE IN THE FORMATION OF THE FACE. www.indiandentalacademy.com
    • THOUGH DEVELOPMENT OF THESE ( ARCHES, CLEFTS & POUCHES ) RESEMBLES FORMATION OF GILLS IN FISHES & AMPHIBIA,IN THE HUMAN EMBRYO REAL GILLS ARE NEVER FORMED. THEREFORE THE TERM PHARYNGEAL ARCHES HAS BEEN ADOPTED. www.indiandentalacademy.com
    • FRONTAL VIEW OF EMBRYO AT 4- 4half WEEKS. www.indiandentalacademy.com
    • FIRST PHARYNGEAL ARCH www.indiandentalacademy.com
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    • SECOND PHARYNGEAL ARCH www.indiandentalacademy.com
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    • THIRD PHARYNGEAL ARCH www.indiandentalacademy.com
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    • FOURTH & SIXTH PHARYNGEAL ARCH www.indiandentalacademy.com
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    • PHARYNGEAL POUCHES • THE HUMAN EMBRYO HAS FIVE FIVE PAIRS OF PHARYNGEAL POUCHES. • THE LAST ONE IS ATYPICAL AND OFTEN CONSIDERED AS PART OF THE FOURTH. • SINCE THE EPITHELIAL ENDODERMAL LINING OF THE POUCHES GIVES RISE TO A NO OF IMPORTANT ORGANS, THE FATE OF EACH POUCH IS CONSIDERED SEPARATELY. www.indiandentalacademy.com
    • FIRST PHARYNGEAL POUCH www.indiandentalacademy.com
    • SECOND PHARYNGEAL POUCH www.indiandentalacademy.com
    • THIRD PHARYNGEAL POUCH www.indiandentalacademy.com
    • FOURTH PHARYNGEAL POUCH www.indiandentalacademy.com
    • FIFTH PHARYNGEAL POUCH www.indiandentalacademy.com
    • PHARYNGEAL CLEFTS www.indiandentalacademy.com
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    • FORMATION OF THE FACE www.indiandentalacademy.com
    • THE FACIAL PROMINENCES www.indiandentalacademy.com
    • • FACIAL PROMIENCES ARE DERIVED FROM THE NEURAL CREST ECTOMESENCHYME. • FRONTO NASAL PROMIENCES, WHICH SURROUNDS THE FOREBRAIN,SPROUTS LATERAL OPTIC DIVERTUCLA THAT FORMS THE EYES. • THE PORTION BETWEEN THE EYES FORM THE FOREHEAD. • AT THE INFEROLATERAL CORNERS ,ECTODERMAL THICKENINGS APPEAR,THE NASAL (OLFACTORY) PLACODES. • THIS IS INDUCED BY THE UNDERLYING OLFACTORY NERVES. www.indiandentalacademy.com
    • • DURING 5TH WEEK THE NASAL PLACODES INVAGINATE TO FORM THE NASAL PITS,WHICH ARE THE PRECURSORS OF THE ANTERIOR NARES. • THIS CREATES A RIDGE OF TISSUE THAT SURROUNDS EACH PIT AND FORMS THE NASAL PROMINENCES. • THE PROMINENCES ON TNE OUTER EDGES OF THE PITS ARE THE LATERAL NASAL PROMINENCES & THOSE ON THE INNER EDGE ARE THE MEDIAN NASAL PROMINENCES. www.indiandentalacademy.com
    • 5TH WEEK EMBRYO www.indiandentalacademy.com
    • UNION OF THE FACIAL PROMINENCES • THIS OCCURS BY TWO DEVELOPMENTAL EVENTS AT DIFFERENT LOCATIONS. • MERGING OF THE FRONTONASAL,MAXILLARY & MANDIBULAR PROMINENCES. MERGING TAKES PLACE AS A RESULT OF MIGRATION INTO & OR PROLIFERATION OF UNDERLYING MESENCHYME INTO THE GROOVE. • FUSION OF THE CENTRAL MAXILLONASAL COMPONENTS. TAKES PLACE BY DISINTEGRATION OF THEIR CONTACTING SURFACE EPITHELIA , ALLOWING INTER - MINGLING OF THE UNDER LYING MESENCHYME. www.indiandentalacademy.com
    • • DURING THE NEXT TWO WEEKS ,THE MAXILLARY PROMINENCES CONTINUES TO INCREASE IN THE SIZE. • GROWS MEDIALLY, COMPRESSING THE MEDIAL NASAL PROMINENCES TOWARDS THE MID LINE. • SUBSEQUENTLY THE CLEFT BETWEEN THEM IS LOST AND THEY FUSE. • FUSION OF THE MEDIAN NASAL & MAXILLARY PROMINENCES PROVIDES CONTINUITY OF THE UPPER JAW & THE LIP. • MID LINE MERGING OF THE MEDIAN NASAL PROMINENCES FORMS THE MEDIAN TUBERCULUM & PHILTRUM OF THE UPPER LIP,THE TIP OF THE NOSE &THE PRIMARY PALATE. www.indiandentalacademy.com
    • 7TH WEEK EMBRYO www.indiandentalacademy.com
    • • THE LOWER JAW & LIP ARE FORMED BY MIDLINE MERGING OF THE PAIRED MANDIBULAR PROMINENCES. • COMMISURES (CORNERS) OF THE MOUTH ARE FORMED BY THE LATERAL MERGING OF THE MAXILLARY & MANDIBULAR PROMINENCES. www.indiandentalacademy.com
    • CHANGE IN THE BLOOD SUPPLY OF THE FACE DURING THE 7TH WEEK www.indiandentalacademy.com
    • NASO LACRIMAL DUCT • PRESENCE OF DEEP FURROW. • MIGRATION OF EPITHELIAL CELLS INTO THE MESENCHYME. • CANALIZATION OF THESE CORDS TO FORM THE NASO LACRIMAL DUCT. • UPPER END WIDENS TO FORM THE LACRIMAL SAC. • DUCT BECOMES PATENT ONLY AFTER THE BIRTH. 7TH WEEK EMBRYO www.indiandentalacademy.com
    • EYES • ON THE VENTROLATERAL ASPECT OF THE DEVELOPING FORE BRAIN , ECTODERMAL THICKENINGS APPEAR AS LENS PLACODE. • THE LENS PLACODE SINKS BELOW THE SURFACE EPITHELIUM & IS EVENTUALLY CUT OF FROM THE SURFACE ECTODERM FORMING THE LENS VESICLE. www.indiandentalacademy.com
    • • AT THIS TIME THE DEVELOPING EYE BALL PRODUCES SIGNIFICANT BULGING . • THESE BULGINGS ARE FIRST DIRECTED LATERALLY. • DUE TO ENORMOUS GROWTH OF THE CEREBRAL HEMISPHERES THE EYES MIGRATE MEDIALLY. • LATER THE EYE LIDS ARE FORMED FROM THE SURFACE ECTODERM. • EYE LIDS REMAIN FUSED UNTIL THE 7TH MONTH OF INTRA UTERINE LIFE & THEN INVADING MUSCLES ALLOWS THEIR OPENING. www.indiandentalacademy.com
    • • FORMED FROM THE DORSAL PART OF THE 1ST ECTODERMAL CLEFT. • APPEARANCE OF SERIES OF MESODERMAL THICKENINGS OFTEN CALLED TUBERCLES OR HILLOCKS. • FORMATION OF PINNA BY FUSION OF THESE THICKENINGS. • WHEN INTIALLY FORMED ARE AT THE NECK REGION BUT WITH THE DEVELOPMENT OF MANDIBLE THEY ASCEND TO THE SIDE OF THE HEAD AT THE LEVEL OF THE EYES. EARS www.indiandentalacademy.com
    • NOSE • FORMED BY COMPLEX CONTRIBUTION FROM THE FRONTAL PROMINENCE (THE BRIDGE) THE MERGED MEDIAN NASAL PROMINENCES (THE MEDIAN RIDGE & THE TIP) THE LATERAL NASAL PROMINENCES (THE ALAE) CARTILAGINOUS NASAL CAPSULE (THE SEPTUM & NASAL CONCHAE) www.indiandentalacademy.com
    • MOLECULAR REGULATION OF FACIAL DEVELOPMENT www.indiandentalacademy.com
    • ARRANGEMENT OF GENES www.indiandentalacademy.com
    • EXPRESSION OF THE HOXB CLUSTER OF HOMEOBOX GENES www.indiandentalacademy.com
    • HOX GENE EXPRESSION IN RHOMB MERES OF THE HIND BRAIN www.indiandentalacademy.com
    • SKELETAL SYSTEM SKULL NEURO CRANIUM • THE MEMBRANOUS PART • THE CARTILAGINOUS PART OR CHONDROCRANIUM VISCERO CRANIUM • BONES OF THE FACE. • FORMED FROM THE FIRST TWO PHARYNGEAL ARCHES www.indiandentalacademy.com
    • MEMBRANOUS NEUROCRANIUM www.indiandentalacademy.com
    • CARTILAGINOUS NEUROCRANIUM OR CHONDROCRANIUM www.indiandentalacademy.com
    • DEVELOPMENT OF FACIAL SKELETON • THE FACE MAY BE CONVIENTLY,IF SOME WHAT ARBITARILY DIVIDED INTO UPPER, MIDDLE & LOWER THIRDS. • THE THREE PARTS CORRESPOND GENERALLY TO THE EMBRYONIC STRUCTURES NAMELY THE FRONTO NASAL, MAXILLARY & MANDIBULAR PROCESS. www.indiandentalacademy.com
    • • UPPER THIRD OF FACE IS PREDOMINANTLY OF NEUROCRANIAL COMPOSITION,WITH THE FRONTAL BONE OF THE CALVARIA ,PRIMARILY RESPONSIBLE FOR THE FORE HEAD. • INTIALLY GROWS MOST RAPIDLY KEEPING PACE WITH ITS NEUROCRANIAL ASSOCIATION & THE PRECOCIOUS DEVELOPMENT OF THE FRONTAL LOBES OF THE BRAIN. • ACHIEVES ITS ULTIMATE GROWTH POTENTIAL AT AN EARLY AGE, PRACTICALLY CEASING THE GROWTH SIGNIFICANTLY AFTER THE 12 YEARS OF LIFE. www.indiandentalacademy.com
    • • MIDDLE THIRD OF FACE IS SKELETALLY THE MOST COMPLEX,BEING COMPOSED IN PART OF THE CRANIAL BASE & INCORPORATING BOTH THE NASAL EXTENSIONS OF THE UPPER THIRD PART OF THE MAXILLARY APPARATUS. • GROWS MORE SLOWLY OVER A PROLONGED PERIOD, NOT CEASING THE GROWTH UNTIL THE LATE ADOLESENCE. www.indiandentalacademy.com
    • • THE LOWER THIRD OF FACE COMPLETES THE MASTICATORY APPARATUS, BEING COMPOSED OF THE SKELETON OF THE MANDIBLE & ITS DENTITION. • GROWS MORE SLOWLY , NOT CEASING THE GROWTH UNTIL THE LATE ADOLESENCE. www.indiandentalacademy.com
    • • FACIAL BONES DEVELOP INTRA MEMBRANOUSLY FROM OSSIFICATION CENTERS IN THE NEURAL CREST MESENCHYME OF THE EMBRYONIC FACIAL PROCESS. • IN THE FRONTONASAL PROCESS,INTRAMEMBRANOUS SINGLE OSSIFICATION CENTER APPEARS IN THE 3RD MONTH. • DURING 8TH WEEK A PRIMARY OSSIFICATION CENTER APPEARS FOR EACH MAXILLA AT THE TERMINATION OF INFRA ORBITAL NERVE JUST ABOVE THE CANINE TOOTH DENTAL LAMINA. • FURTHER TWO INTRA MEMBRANOUS PREMAXILLARY CENTERS APPEAR ANTERIORLY ON EACH SIDE IN THE 8TH WEEK & RAPIDLY FUSE WITH THE PRIMARY MAXILLA. • THE MANDIBULAR PROCESS DEVELOP BILATERALLY FROM A SINGLE INTRA MEMBRANOUS CENTRE. www.indiandentalacademy.com
    • THE ATTACHEMENT OF THE FACIAL SKELETON ANTERO – INFERIORLY TO THE CALVARIA DETERMINES THE CHONDRO CRANIAL INFLUENCE ON FACIAL GROWTH. www.indiandentalacademy.com
    • CONCLUSION JUST AS THE CLINICIAN NEEDS THE MEDICAL HISTORY TO MAKE A LOGICAL DIAGNOSIS, SO TOO THE GROWTH AND DEVELOPMENT OF FACE IS ESSENTIAL FOR A LOGICAL EXPLANATION OF ANY STRUCTURAL AND FUNCTIONAL IMBALANCES IF IT DO OCCURS. www.indiandentalacademy.com
    • REFERENCES • SPERBER EMBRYOLOGY. • LANGMANS EMBRYOLOGY - 8TH EDITION. • GRAYS ANATOMY – 38TH EDITION. • FUNDAMENTALS OF CRANIOFACIAL GROWTH – Edited by ANDREW D. DIXON. • CONTEMPORARY ORTHODONTICS – 3RD EDITION Edited by WILLIAM R.PROFFIT. • HAND BOOK OF ORTHODONTICS – 4TH EDITION Edited by ROBERT E MOYERS. • ORTHODONTICS,PRINCIPLES & PREVENTION – Edited by J A SALZMANN. • ESSENTIALS OF FACIAL GROWTH – ENLOW & HANS. www.indiandentalacademy.com
    • THANK YOU www.indiandentalacademy.com For more details please visit www.indiandentalacademy.com