Kharkov National Medical University Department of Histology, cytology and embryology LECTURE for dentistry students 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 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 Pharyngeal Pouches Ectoderm Frontal process 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 MAXILLARY PROCESSES grow to meet just off the midline, which is occupied by the fusing medial nasal processes Olfactory pit FACE FRONTONASAL REGION gets back by merging nasomedial processes 7-w/19mm EMBRYO EYE NASOMEDIAL PROCESS MOUTH MANDIBULAR PR. HYOID BONE MAXILLARY PROCESS 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 MEDIAN CLEFT JAW UNILATERAL MACROSTOMIA mouth too wide (microstomia - too small) MEDIAN CLEFT LIP Nose may also be cleft UNILATERAL CLEFT LIP 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 Lateral palatines CLEFT UVULA ANTERIOR CLEFT PALATE Incomplete & Unilateral PALATAL DEFECTS II: Failures to fuse POSTERIOR CLEFT PALATE COMPLETE UNILATERAL ANTERIOR CLEFT Palate & Lip PALATE Can occur independently; can be partial; anterior can be bilateral 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 TOOTH LIP LIP HARD PALATE SOFT PALATE TONGUE ORAL STRUCTURES Sagittal view SALIVARY GLANDS ALVEOLAR BONE + CHEEK GUM ORAL MUCOSAE: Classification MASTICATORY (CHEWING) HARD PALATe GINGIVAe SPECIALIZED DORSAL LINGUAL LINING (COVERING) LABIAL BUCCAL ALVEOLAR SOFT PALATAL Epithelium undergoes keratinization LIP 2. RED MARGIN VERMILION transitional 1. HAIRY SKIN anterior MUSCLE 3. LABIAL MUCOSA thick inner GLAND mucous GUM (GINGIVA) FREE GINGIVA ATTACHED GINGIVA c.t. } Epithelial attachment TOOTH Gingival sulcus/ crevice/FISSURE HARD PALATE: Cross-section PALATE BONE why it is hard! 2. Palatal seam STRATIFIED SQUAMOUS EPITHELIUM slightly-keratinized Periosteum 1.Fatty zone – anterior 3. Glandular zone MUCOUS GLANDS - posterior TONGUE - dorsum TONSILS CIRCUMVALLATE PAPILLA FILIFORM PAPILLAE General sensation FUNGIFORM PAPILLA Taste bud Trench FOLIATE PAPILLAE on the lateral t. SALIVARY GLANDS - major & minor Parotid Sub-lingual Sub-mandibular MINOR Labial. Buccal. Lingual. Palatal PROTECTION SALIVA – Functions ALIMENTARY Mastication Swallowing Digestion OTHER Vocalization Excretion Epithelial lubrication Anti-microbial materials For tooth: Rinsing Buffering Mineralization MATERIALS: Water Mucins (glycoproteins) Antibodies IgAs Lysozyme Defensins Ions - tooth mineral Amylase Iodine SCHEME OF SALIVARY GLANDS SECRETORY UNITS Lobule } General duct Interlobular duct STRIATED duct Intercalated ducts See SALIVA Powerpoint 2. MUCOUS TUBULE 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) STRIATED DUCT (few) INTER LOBULAR DUCT MIXED MUCOUS TUBULES SEROUS demilune MUCOUS LE image1.jpeg image2.jpeg image3.jpeg image4.jpeg image5.jpeg image6.jpeg image7.jpeg image8.jpeg image9.jpeg image10.png image11.jpeg image12.jpeg image13.jpeg image14.png image15.wmf WABeresford