Kharkov National Medical University LECTURE for dentistry students Department of Histology, cytology and embryology

MICROMORPHOLOGY AND EMBRYOLOGY OF THE ORAL CAVITY

FACE AND ORAL CAVITY ORGANS DEVELOP FROM MESENCHYME, ECTODERM AND ENDODERM On the 3-4-th week the stomatodaeum (oral bay - ectodermal invagination ) is formed. This will fuse with the gut through oropharyngeal membrane.

Oropharyngeal Membrane Amnion gut Stomatodaeum Yolk sac

Pharynx wall forms 4 thickenings –pharyngeal arches

1. Each consists of mesenchyme, outer ectoderm and inner endoderm. 2. Arches mesenchyme provides the skeletal muscle and c.t. 3. They form: 1) face, nasal cavities, 2) mouth, larynx, 3) pharynx, and neck.

Development of oral cavity begins with the formation of frontal process over the oral bay and growth of the 1-st ph. arch, which divides on: – maxillar and mandibular processes

Frontal process Ectoderm Pharyngeal Pouches

Frontal Process Maxillary Mandibular

In the frontal process are formed olfactory pits. They divide f.p. on medial and lateral nasal processes – Latter fuse with maxillar and mandibular processes and nose and lips appear

Olfactory pit NASOMEDIAL PROCESS Nasolateral process MAXILLARY PROCESSES grow to meet just off the midline, which is occupied by the fusing medial nasal processes FRONTONASAL REGION gets back by merging nasomedial processes FACE

7-w/19mm EMBRYO NASOMEDIAL PROCESS EYE MAXILLARY PROCESS MOUTH MANDIBULAR PR. HYOID BONE LARYNGEAL CARTILAGES FACE

This causes nursing problem for the new born. Malformation 1.Clefts involving the upper lip 2.Unilateral and 3.Bilateral cleft lip result if maxillary and medial nasal processes do not fuse. 4. Cleft palate leaves the nasal and oral cavities connected. This causes nursing problem for the new born.

FACIAL DEFECTS: UNILATERAL CLEFT LIP OBLIQUE FACIAL CLEFT MEDIAN CLEFT JAW UNILATERAL MACROSTOMIA mouth too wide (microstomia - too small) MEDIAN CLEFT LIP Nose may also be cleft UNILATERAL CLEFT LIP FACE

Bilateral Facial clefts and bilateral cleft lip Cleft Upper lip “hairlip”

PALATE developes by fushion of maxillar processes

PALATAL DEFECTS I: Partial failures to fuse UNILATERAL CLEFT LIP ANTERIOR CLEFT PALATE Incomplete & Unilateral CLEFT UVULA Lateral palatines

PALATAL DEFECTS II: Failures to fuse COMPLETE UNILATERAL ANTERIOR CLEFT Palate & Lip POSTERIOR CLEFT PALATE Can occur independently; can be partial; anterior can be bilateral PALATE

Sources of Tongue development ARCH I II III IV ARCH I ARCH III Terminal sulcus TONGUE

TONGUE MALFORMATIONS I ARCH I II III IV LATERAL LINGUAL SWELLINGS Failure of these to fuse properly causes a DEEP MEDIAL SULCUS or at worst a SPLIT TONGUE Overgrowth - MACROGLOSSIA Undergrowth - MICROGLOSSIA TONGUE

ORAL CAVITY IS LINED BY MUCOSA, CONSISTS OF STRATIFIED NONKERATINIZED EPITHELIUM AND C.T. LAMINA PROPRIA FUNCTIONS: 1. PROTECTIVE 2. SECRETORY 3. SENSORY

TONGUE ORAL STRUCTURES Sagittal view TOOTH LIP HARD PALATE SOFT PALATE SALIVARY GLANDS ALVEOLAR BONE + CHEEK GUM

MASTICATORY (CHEWING) ORAL MUCOSAE: Classification MASTICATORY (CHEWING) Epithelium undergoes keratinization HARD PALATe GINGIVAe SPECIALIZED DORSAL LINGUAL LINING (COVERING) LABIAL BUCCAL ALVEOLAR SOFT PALATAL

LIP 1. HAIRY SKIN anterior 2. RED MARGIN VERMILION transitional 3. LABIAL MUCOSA thick inner GLAND mucous 1. HAIRY SKIN anterior MUSCLE

} GUM (GINGIVA) TOOTH Gingival sulcus/ crevice/FISSURE FREE GINGIVA ATTACHED GINGIVA c.t. } Epithelial attachment TOOTH Gingival sulcus/ crevice/FISSURE

3. Glandular zone MUCOUS GLANDS HARD PALATE: Cross-section PALATE BONE why it is hard! Periosteum 2. Palatal seam 1.Fatty zone – anterior 3. Glandular zone MUCOUS GLANDS - posterior STRATIFIED SQUAMOUS EPITHELIUM slightly-keratinized

TONGUE - dorsum CIRCUMVALLATE PAPILLA FUNGIFORM PAPILLA TONSILS CIRCUMVALLATE PAPILLA Trench FUNGIFORM PAPILLA FILIFORM PAPILLAE General sensation Taste bud FOLIATE PAPILLAE on the lateral t.

SALIVARY GLANDS - major & minor Parotid Sub-mandibular Sub-lingual MINOR Labial. Buccal. Lingual. Palatal

SALIVA – Functions Anti-microbial materials PROTECTION Mastication ALIMENTARY Mastication Swallowing Digestion OTHER Vocalization Excretion Epithelial lubrication Anti-microbial materials For tooth: Rinsing Buffering Mineralization

Mucins (glycoproteins) Antibodies IgAs MATERIALS: Water Mucins (glycoproteins) Antibodies IgAs Lysozyme Defensins Ions - tooth mineral Amylase Iodine

} General duct Lobule SCHEME OF SALIVARY GLANDS Interlobular duct SECRETORY UNITS } General duct Lobule Interlobular duct STRIATED duct Intercalated ducts See SALIVA Powerpoint

1. SEROUS ALVEOLUS 2. MUCOUS TUBULE BL 3. MIXED UNIT SEROUS DEMI-LUNE MYOEPITHELIAL CELL SEROUS DEMI-LUNE BL 1. SEROUS ALVEOLUS 3. MIXED UNIT with

PAROTID GLAND (serous) SEROUS ACINi STRIATED DUCT INTERCALATED DUCT INTER LOBULAR DUCT

SUBMANDIBULAR GLAND (sero-mucous) SEROUS ACINi INTRA LOBULAR DUCT INTER LOBULAR DUCT A FEW MIXED units SEROUS demilune

SUBLINGUAL GLAND (muco-serous) INTER LOBULAR DUCT MIXED MUCOUS TUBULES SEROUS demilune MUCOUS LE STRIATED DUCT (few)