Kharkov National Medical University LECTURE for dentistry students

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 Stomatodaeum Amnion Yolk sac gut

• Pharynx wall forms 4 thickenings – pharyngeal arches Pharynx

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

Ectoderm Frontal process 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

NASOMEDIAL PROCESS Nasolateral process Olfactory pit 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/19 mm EMBRYO NASOMEDIAL PROCESS EYE MAXILLARY PROCESS MOUTH MANDIBULAR PR. HYOID BONE LARYNGEAL CARTILAGES FACE

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

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

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 Terminal sulcus II IV ARCH III TONGUE

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

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

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

LIP 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 Epithelial attachment ATTACHED GINGIVA c. t.

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 slightlykeratinized

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

SALIVARY GLANDS - major & minor Parotid Submandibular MINOR Labial. Buccal. Lingual. Palatal Sublingual

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

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

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

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

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

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

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