Oral Histology and Embryology PRACTICE Mgr. Jan Křivánek, Ph.D. 1. practice Introduction Cards, sitting order Organisation of practice Attendance and substitution of missed lessons Protocols Safety rules Oral Histology and Embryology PRACTICE Samples: • labium oris (1) • palatum molle (5) • apex linguae (2) • papilla vallata (3) Microscopic anatomy Lips Tongue Palate Cheeks Oral cavity (cavitas oris) vestibulum oris / cavitas oris propria Borders Lips, cheeks, hard and soft palates, caudally floor of cavity, faucial isthmus (connection to oropharynx) Inside Tongue, teeth, gums, tonsilla palatina Major salivary glands: gl. submandibulatis gl. sublingualis gl. parotis Cook, Sarah et al. A food perspective. Food Hydrocolloids. 2017. Oral mucosa epithelium thick stratified squamous • Masticatory mucusa • (Specialized mucosa) Oral mucosa nonkeratinized keratinized • Lining mucosa Lamina propria mucosae Contains numerous of melanocytes or melanophages Multiple papilae projected against the epithelium. Their shape and density are spatially different (depends on different mechanical needs of oral mucosa) Oral mucosa classification Lining (65 %) Inner part of lips, cheeks soft palate, inferior aspect of the tongue, floor of the mouth and alveolar process (except of the gingiva) tela submucosa located under mucosa soft and slightly movable (submucous coat) lamina propria from loose connective tissue Masticatory (25 %) Hard palate and gingiva epithelium keratinized tela submucosa is missing lamina propria composed from dense collagenous of irregular type and firmly connected with periosteum (mucoperiosteum) Specialized (10 %) dorsal surface of the tongue mucosa protrudes into papillae tela submucosa is missing lamina propria connected with aponeurosis linguae B, In histologic sections, the gingival epithelium is seen to be tightly bound to bone by a dense fibrous connective tissue (CT), whereas the epithelium of the lip (C) is supported by a much looser connective tissue. Gingiva Lip • Lamina propria from dense collagenous connective tissue of irregular type • Firmly connected to periosteum (mucoperiosteum) • Lamina propria from loose collagenous tissue • Tela submucosa under mucosa • Mucosa is slightly movable Epithelium Lamina propria Mucosa Tela submucosa Lining mucosaMasticatory mucosa Oral mucosa regeneration Oral epithelium turnover time: 4 - 24 days Significant local differences Gingivo-dental junctional epithelium 4-6 days Gingiva affixa epith. (masticatory mucosa) 10 days Taste buds 10 - 14 days Lining epith. of lips and cheeks mucosa 14 days Lining epith. of the floor of mouth 20 days Masticatory epithl. of hard palate 24 days Epidermis of the face and neck frontal side 7 days Epidermis (rest) 30 days (faster turnover time in case of the face is probably caused by inductive effect of the ectomezenchyme) Waasdorp, et al., 2021 Mak, et al., 2009 desJardins-Park, et al., 2019 Lip Sagitally: • ventral aspect of the lip • dorsal aspect of the lip a) lamina epithelialis mucosae stratified squamous epithelium b) lamina propria mucosae loose areolar connective tissue • m. orbicularis oris • vermilion zone Why do the lips have a red color? Vermilion zone glandulae labiales (mixed) Ret (mucous side) lamina propria tela submucosa Sebaceous glands Hair follicle Lip (skin side) ? Adult Suckling pars villosa pars glabra pars mucosa PG - pars glabra (Glabra = flat) PV - pars villosa (Villosa = vilous) (PM - pars mucosa) Newborns vermilion zone can be divided into: Newborns vermilion zone ventral (skin) and dorsal (mucous) side are connected by vermilion zone NEWBORNS vermilion zone can be divided into: pars glabra (2 mm) more narrow, ventral pars villosa (asi 4 mm) wider, dorsal Pars glabra • Stratified squamous epithelium with keratinization signs • Lamina propria protrudes by higher papillae than dermal papillae • In 50 % small sebaceous glands are in lamina propria Pars villosa • Thick stratified squamous epithelium • Numerous and slender papillae, which form the labial torus (torus labialis) • Papillae are HIGHLY VASCULARIZED and contains numerous of sensitive NERVE ENDINGS • Facilitates firm connection with the nipple during breastfeeding zonation of the vermillion zone disappears with advanced age of a child Vermilion zone Cheek (bucca) Histologically similar to the lip https://www.brainyoo.de/Brainyoo2Web/ wikipedia Corpus adiposum buccae Between m.buccinator and m. masseter: palatum durum palatum mole Palate Hard palate (palatum durum) Masticatory mucosa: • Epithelium stratified squamous keratinizing • Tela submucosa missing Adipous zone Glandular zone raphe palati Huge regional variability: Local differences in hard palate structure Palatal raphe • Midline from the incisive papilla to soft palate, mucosa without glandulae and adipocytes Foramen incisivum • Location on the papilla incisiva • Maintains connection with nasal cavity before birth is closed Adipose zone • Paired structure • Medially divided by papilla incisiva and raphe palati, Laterally bordered by gingiva and premolars • Mucosa is thickened into 3-5 transversal plicae - plicae palatinae transversae, core of plicae is formed by stripes of dense colagenous connective tissue interlaced with adipocytes Glandular zone • Paired structure • Mucosa is smooth and contains true mucous glands – gll. palatinae Hard palate – glandular zone (frontal view) glandulae palatinae Vomeronasal organ (organon Jacobsoni) • RUDIMENTARY in human • Under nasal septum musosa anteriorly to and above the incisive duct • 2- 6 mm long, dead-end thin canal • Well developed in reptiles - the olfactory organ • Chemoreceptors Nasal side Oral side aponeurosis Pseudostratified epithelium Stratified squamous nonkeratinized epithelium Soft palate (palatum molle) uvula Transitional zone on nasopharyngeal side Mixed gll. nasales (nasal side) Tela submucosa Oral mucosa (lining type) gll. palatinae Soft palate(palatum molle) • Movable mucosal fold terminated by a uvula – uvula (gr. staphylos) • Interposed between the oral cavity and nasal fossae Core tissue - aponeurosis palatina, composed of tendons and muscles of striated muscles (mostly m. tensor veli palatini) - Nasal aspect - mucosa of respiratory passages and tela submucosa with mixed glandulea (glandulae nasales) - Oral aspect - lining mucosa, dorsally passes to the nasal aspect (over uvula) between mucosa nad aponeurosis is submucous coat with mucinous glandulae (glandulae palatinae) Tongue Lingua (lat.) Glossa (gr.) radix Base: intra- and extraglossal striated muscles Evulutionary: developed in terrestrial vertebrates and amphibians (tetrapods) from muscles of oral floor Surface Dorsum linguae Specialized oral mucosa Inferior aspect Lining mucosa Fibrous parts aponeurosis linguae very stiff fibrous membrane septum linguae Composed from dense collagenous tissue Dorsum lingue Specialized oral mucosa • Firmly connected with aponeurosis linguae • Rough surface • Mucosal outgrowths - lingual papillae • Covered by nonkeratinized squamous stratified epithelium (except of papillae filiformes) Papillae fungiformes Mushroom-shape (0.5-1.5 in height, 0.5–1.0 mm in width) Taste buds in epithelium Papillae filiformes The most abundant and distributed over the entire dorsal surface of the tongue; Brush-like appearance (0.5-1 mm in height, 0.2-0.3 mm in width); The stratified squamous epithelium is often cornified Keratinisation differences Taste bud Papillae vallatae (Papila circumvallata) Largest (1-4 mm in height, 1-3 mm in width), 7–12 just in front of sulcus terminalis, submerged into mucosa. Deep circumpapillary furrow. Taste buds Duct (V) of Ebner´s gland opening on bottom of an circumpapillary furrow. Taste bud Basic tastes: Sweet Salty Sour Bitter Umami Suggested: Fatty Metalic TASTE ? Samples: • labium oris (1) • palatum molle (5) • apex linguae (2) • papilla vallata (3)