Oral Cavity & Salivary Glands Lecture Notes PDF

HISTOLOGY & EMBRYOLOGY: LE3 | TRANS 01 ORAL CAVITY & SALIVARY GLANDS DR. DESIDERIO | 11/07/2024 d OUTLINE ○ Lining Mucosa...

HISTOLOGY & EMBRYOLOGY: LE3 | TRANS 01 ORAL CAVITY & SALIVARY GLANDS DR. DESIDERIO | 11/07/2024 d OUTLINE ○ Lining Mucosa Found on the lips, cheeks, alveolar I. Oral Cavity III. Major Salivary Glands A. Lips A. Parotid Gland mucosal surface, floor of the mouth, B. Teeth B. Submandibular inferior surfaces of the tongue, and II. C. Tongue Salivary Glands Gland C. Sublingual Gland ❗ soft palate (Everything else above) Stratified Squamous Non-Keratinized Epithelium. A. Salivary Secretory Unit Cell Types B. Duct System of Large Salivary Glands SUMMARY OF ABBREVIATIONS LEGENDS ❗ 👩‍⚕️ 📖 🖥 📝 Must know Lecturer Book Presentation Old Trans LEARNING OBJECTIVES At the end of the lecture, the student should be able to: ✔ Recognize and describe the histological features of the oral cavity ✔ Identify and differentiate between the various types of salivary glands Figure 1. Anatomy of the Oral Cavity [supplementary resource online] ❗ ORAL CAVITY 👩‍⚕️ Lined with Stratified Squamous Epithelium Keratinized, partially keratinized, or nonkeratinized, LIPS 📖 depending on which part of the oral cavity ○ 📖 Well-developed core of striated muscle Makes the lip highly mobile 📖 Keratinization depends on the location and risk of abrasion ○ Keratinized (Dry Type) Gingiva; Hard Palate ○ ❗ Internal Mucous Surface Lined with Nonkeratinized (Stratified) Epithelium with salivary glands or minor salivary glands Needs Resistance Vermilion Zone Prone to friction which needs more 📖 ❗ ○ Moist area between the lip and facial skin keratinization ○ Keratinized (Stratified) Epithelium ○ 📖 Masticatory mucosa Non-Keratinized (Wet Type) 📖 Outer Surface of the Lips 📖 ○ Made up of thin skin with epidermal and dermal layers Soft Palate, Cheeks, Floor of the Mouth, Pharynx ○ (+) Sweat glands and hair follicles Contains a lot of minor salivary glands which secretes continuously to keep the mucosa wet Boundaries Front: lips Above: hard & soft palate 👩‍⚕️ Below: floor of mouth, tongue Divided into: ○ Oral vestibule Space between lips, cheek, and teeth ○ Oral cavity proper Behind teeth, bounded by hard & soft palate and floor of mouth, including the tongue inferiorly Figure 2. Anatomy of the Lips [supplementary resource online] Retromolar space ○ Is lined by the oral mucosa Forms an important protective barrier between the external environment of the oral cavity and internal environments of the surrounding tissue. Consists of: ○ Masticatory Mucosa found on the gingiva (gums), hard ❗ palate and dorsum of the tongue Stratified squamous keratinized epithelium LE 3 Trans 1 TG: Borneo, Lumawag, Malabag | Lerio, Ong Lo Page 1 of 8  📖○ Pulp📖Cavity Extends from the neck into the apical foramina of the ○ 📖Composed of well-vascularized and well-innervated root tips Figure 3. Section of the Lip: (OM) Oral Mucosa, (S) Skin, (F) Follicle, (V) Vermillion Zone, (M) Striated Muscle, (G) Minor Salivary Glands [Junquiera] TEETH 📖 32 permanent teeth Figure 5. Molar with parts of the tooth indicated[Junqueira] 📖 ○ Adults: 32 permanent teeth ○ Twenty of the permanent teeth are preceded by Dentin deciduous (primary) teeth that are eventually shed; others are permanent molars with no deciduous 📖 Teeth is mostly covered by dentin (softer than enamel) Bulk of the tooth is calcified material/tissue called dentin 📖 precursors Arranged in two bilaterally symmetric arches in the maxillary 📖 which surrounds the internal pulp cavity Dental pulp is highly vascular and well innervated and and mandibular bones consists largely of 16 upper and lower set Loose, mesenchymal connective tissue with much: Each quadrant has eight teeth: Ground Substance ○ (1) One canine Thin Collagen Fibers ○ (2) Two incisors (1 central + 1 Lateral) Fibroblasts ○ (2) Two premolars And mesenchymal stem cells ○ (3) Three permanent molar Composed of: ○ 70% Hydroxyapatite ○ Organic Matrix Type 1 Collagen Proteoglycans (secreted from odontoblasts) 📖Pulp Odontoblasts ○ penetrates the full thickness of the dentin ○ Secretes predentin, precursor of dentin Loose Connective Tissue Enamel Acts as the covering of the crown Trivia: Hardest component of the human body Composed of: ○ 96% Calcium Hydroxyapatite ○ 2% to 3% Organic Material ○ No Collagen Ameloblast ○ Tall/Columnar in shape ○ Secretes enamel matrix Enamel Rods Figure 4. Permanent Teeth[Junquiera] ○ Elongated rods that extend out through the entire Parts of Each Tooth thickness of the enamel layer Crown Periodontium ○ Covered by enamel (hard and acellular) ○ Exposed above the gingiva The one keeping your teeth attached to your dental sockets Neck (maxillary and mandibular bones) ○ Constricted at the/by the gum Components: Root ○ Cementum Produced by cementocytes ○ 📖 Has one or more roots covered by sementum Contains Dentin, avascular 📖 ( cementum) that are firmly attached into bony sockets in the jaw called dental alveoli ( ) or your dental Covers the dentin of the root and resembles bone 📖 sockets. Thickest around the root tip where cementocytes ○ note that cementum and enamel will eventually meet reside in the lacunae with process in canaliculi at the neck of the tooth especially near the cementum surface LE 3 Trans 1 TG: Borneo, Lumawag, Malabag | Lerio, Ong Lo Page 2 of 8  ○ 📖 Periodontal Ligament Fibrous tissue with bundled collagen that connects your cementum and alveolar bone of tooth socket ○ 📖 Alveolar Bone Immediate contact with periodontal ligament which serves as its periosteum Vessels run through the alveolar bone and penetrated the periodontal ligament along the root of the tooth ○ 📖 Gingiva 📖 Keratinized Stratified Squamous Epithelium Firmly bound to the periosteum of the maxillary and mandibular bones Figure 8. A - Periodontium: (FG) Free Gingive, (LP) Lamina Propria, (P) Periosteum, (D) Dentin, (B) Alveolar Bone, (PL) Periodontal Ligament. B - Blood : (V) Blood Vessels, (L) Periodontal Ligament, (C) Cementum [Junquiera] 📖TONGUE ❗Discretion in studying this section (tongue, lingual papillae, taste buds) as this isn’t part of the lecture proper and ppt, but it is part of the chapter in Junquiera. After taste buds will follow back to the flow of the lecture proper. Mass of striated muscle covered by mucosa, which manipulates ingested material during mastication and swallowing Contains many muscle fibers that are oriented in different directions, allowing a high level of mobility Lower Surface ○ Smooth with typical lining mucosa Dorsal Surface ○ Anterior ⅔: Irregular, with hundreds of Papillae ○ Posterior ⅓: Massed lingual tonsils Sulcus Terminalis ○ V-shaped groove that separates the papillary and tonsilar areas of the lingual surface of the tongue Figure 6. (O) Odontoblasts, (D) Dentin, (PC) Developing Pulp Cavity, (OP) Odontoblast Process, (P) Predentin [Junquiera] Figure 8. Anatomy of the Tongue on the Dorsal surface with Sample Histological Slides on the different taste buds [Junquiera] Figure 7. (CT) Connective Tissue, (A) Ameloblast, (E) Enamel, (D) Dentin [Junquiera] 📖Lingual Papillae Elevations of the mucous membrane that assume various forms and functions. There are 4 types ○ Filiform Papillae ○ Fungiform Papillae ○ Foliate Papillae ○ Circumvallate/Vallate Papillae LE 3 Trans 1 TG: Borneo, Lumawag, Malabag | Lerio, Ong Lo Page 3 of 8  ○ Tastants detected: Table 2. Tastants Tastant Taste Na+ Salty H+ Sour, from acids Sugars Sweet Alkaloid & Toxins Bitter Amino Acids Umami Location: ○ Lingual Papillae (+) in Vallate Papillae (+) in Fungiform (+) in Foliate (-) in Filiform ○ Dorsal and Lateral surfaces of the tongue Figure 9. (F) Fungiform Papillae, (FL) Filiform Papillae, (SS) Stratified Scattered across the surfaces Squamous Epithelium, (CT) Connective Tissue [Junquiera] Components ○ Gustatory Taste Cells Table 1. Types of Lingual Papillae Receptors found in the apical ends that project Filiform Fungiform Foliate Circumvallate/ towards the taste pore Papillae (FL) Papillae (F) Papillae Vallate 7-10 day lifespan Papillae ○ Supportive Cells Heavily Contains Slender, Immature cells Keratinized to taste buds provide a (TB) around ○ Basal/Stem Cells rough surface the sides and Slowly divides to give rise to the other cell types Several Characteristics to facilitate several small, Lightly parallel ridges ○ Base of each bud lies on the basal lamina and is entered movement serous Keratinized on each side by afferent sensory axons that form synapses with the during salivary (von of the tongue gustatory cells chewing Ebner) glands (GL) surrounding the papillae Very Eight to Less Difficult to numerous in twelve are Numerous locate number aligned Elongated Forms a conical shape V-shaped row Mushroom immediately Shaped anterior to the sulcus terminalis Figure 11. Component of a Taste Bud[Junquiera] SALIVARY GLANDS Exocrine glands in the mouth produce saliva for digestive, lubricating, and protective function Normal pH of 6.5-6.9 (has a buffering function) Salivon - basic secretory unit of salivary glands Saliva also has an important buffering function and in some species is also important for evaporative cooling. Three pairs of large salivary glands: (As to size) ○ Parotid Gland (serous and watery) ○ Submandibular Gland (mixed) Figure 10. Large Vallate Papillae: (TB) Taste Buds, (CT) Connective Tissue , ○ Sublingual Gland (mixed) (SS) Stratified Squamous Epithelium, (GL) Salivary Glands[Junquiera] Three epithelial cell types comprise the salivary secretory units: 📖Taste Buds (As to secretion) ○ Serous Mechanism: ○ Mucous ○ Molecules (tastants) dissolved in saliva contact the ○ Mixed microvilli through the pore and interact with cell surface taste receptors Other minor glands: usually located at submucosa of different parts of the oral cavity; produces mostly mucous secretion 📝 LE 3 Trans 1 TG: Borneo, Lumawag, Malabag | Lerio, Ong Lo Page 4 of 8  ○ Buccal ○ Lingual ○ Labial ○ Molar ○ Palatine SALIVARY SECRETORY UNIT CELL TYPES Serous Cell Are polarized protein-secreting cells Usually pyramidal in shape, with round nuclei, well-stained RER, and apical secretory granules. Joined apically by tight and adherent junctions Serous cells form a somewhat spherical unit called an acinus, with a very small central lumen. Serous acinar cells secrete enzymes and other proteins. Figure 14. Ultrastructure of Serous and Mucous cells: (L) Lumen, (M) Mucous Cells [has hydrophilic granules like goblet cells, (S) Serous Cells [have small dense granules, (My) Small Myoepithelial Cells [Junquiera] Figure 12. Serous Cell[Previous Trans] Mucous Cell Somewhat more columnar in shape, with more compressed basal nuclei Contain apical granules with hydrophilic mucins that provide lubricating properties in saliva but cause poor cell staining in routine preparations most often organized as cylindrical tubules rather than acini. Mixed salivary glands have tubuloacinar secretory units with both serous and mucous secretion. Figure 15. Salivary Secretory Unit Cell Types [Essentials of Dental Anatomy & Oral Histology 2014] DUCT SYSTEMS OF LARGE SALIVARY GLANDS Intralobular Ducts Main ducts of the salivary glands Constitute the principle ducts of each salivary glands Found between the lobules of the gland 📝 Lined by Stratified Columnar Epithelium SCE is in general dahil iba-iba ang lining nito sa book. Small excretory duct - simple cuboidal then gradually changes in the lining as the excretory duct become larger As it approaches the opening (within the mouth) it becomes Figure 13. Mucous Cell[Previous Trans] stratified squamous epithelium. Kaya if tinanong “what is the lining epithelium in general?”, it is Myoepithelial Cell SCE. Found inside the basal lamina surrounding acini, tubules, Excretory duct of parotid is Stensen’s and the proximal ends of the duct system Submandibular gland duct is Wharton’s Small and flattened cells extend several contractile processes around the associated secretory unit or duct and Intercalated Ducts their activity is important for moving secretory products into Continuous with the lumen of the acinus and through the ducts Lined by simple cuboidal epithelium Located between the secretory acinus and a larger duct Secretes bicarbonate going into the acinar product and absorb chloride from the acinar prada LE 3 Trans 1 TG: Borneo, Lumawag, Malabag | Lerio, Ong Lo Page 5 of 8 Striated Ducts With striations found in the infranuclear portion Lined by simple columnar epithelium Striated ducts reabsorb Na+ ions from the initial secretion and their folded cell membranes present a large surface area with ion transporters Facilitating rapid ion transcytosis and making the secretion 📝 slightly hypotonic. Functions to reabsorb sodium from the primary secretion and secretes potassium and bicarbonate going into the secretion Figure 17. Micrograph of Parotid Gland shows densely packed Acini (A) with duct : (SD) Striated Ducts, (A) Serous Acini, (ID Intercalated Disc) [Junquiera] Figure 16. Epithelial Components and the Ducts [Junquiera] MAJOR SALIVARY GLANDS PAROTID GLAND Located in each cheek near the ear Are branched acinar glands with exclusively serous acini Serous cells of parotid glands secrete: ○ Abundant α-amylase that initiates hydrolysis of carbohydrates ○ Proline-rich proteins with antimicrobial and other protective properties. Figure 18. Ducts with (+) Serous and Mucous Cells [supplementary resource online] Parotid Ducts ○ travels from the gland and enter the oral cavity opposite SUBMANDIBULAR GLAND the second upper molar tooth Produce two-thirds of all saliva The largest of the major salivary glands Are branched tubuloacinar glands Branched acinar glands with exclusively serous acini Having primarily serous acini, but with many mixed tubuloacinar ○ serous and surround numerous, long, narrow secretory units intercalated ducts Having a crescent-shaped arrangement called “serous ○ Striated ducts are large and conspicuous demilune” Serous Cells in Submandibular secretes the following for hydrolysis of bacterial walls: ○ α-amylase ○ proline-rich proteins ○ lysozyme The duct system of the submandibular gland is similar to that of the parotid gland. ○ The small intralobular intercalated ducts have small lumina and are shorter. ○ The striated ducts with distinct basal striations in the cells are longer than in the parotid gland. LE 3 Trans 1 TG: Borneo, Lumawag, Malabag | Lerio, Ong Lo Page 6 of 8  REFERENCES 1. Mescher, A. (2018). Junquiera’s Basic Histology: Text and Atlas (15th ed.). Mcgraw-Hill Education. 2. Powerpoint: Dr. Desiderio, J. (2024). Oral Cavity & Salivary Glands REVIEW QUESTIONS 1. When the tooth is damaged, these cells are stimulated to repair it A. Predentin B. Ameloblasts C. Odontoblasts D. Cementocytes 2. Teeth are sensitive to stimuli, which can be perceived as pain due to: A. Immune defenses in the oral cavity B. unmyelinated nerve fibers that extend into dental tubules C. Gradual reduction of size of the pulp cavity D. Enamel rod misaraangement 3. What is the lining epithelium of the interlobular excretory duct as it approaches the opening within the mouth> Figure 19.The submandibular gland is a mixed serous and mucous gland (serous cells predominate), and shows: (A) Serous Acini, (S) Serous Demilunes, A. Simple cuboidal epithelium (M) Pale Staining Mucous cells grouped as tubules in a tubuloacinar gland, (ID) B. Stratified columnar epithelium Small Intralobular Ducts that drain each lobule [Junquiera] C. Stratified squamous epithelium D. simple squamous epithelium C. SUBLINGUAL GLAND 4. What duct system reabsorbs sodium and secreted potassium Smallest of the paired major salivary glands and bicarbonate going into the secretion? Located in the floor of the mouth anterior to the submandibular A. Striated duct glands B. Intercalated duct ○ Their multiple small sublingual ducts empty into the C. Interlobular excretory duct submandibular duct as well as directly onto the floor of D. Both A & B the mouth. 5. Which of the ff. are components of the periodontium? Some of the predominant mucous acini exhibit serous demilunes, but purely serous acini are rarely present I. Gingiva ○ few serous cells present add amylase and lysozyme to II. Cementum the secretion III. Alveolar Bone ○ Intercalated ducts and striated ducts are short, difficult to IV. Periodontal Ligament locate, or sometimes absent. Branched tubuloacinar glands A. I, II, II, IV ○ The mucous secretory units may be more tubular than B. I, II, & III purely acinar C. I & III D. II & IV ANSWERS: 1C, 2B. 3C, 4A, 5A Figure 20.The sublingual gland is a mixed but largely mucous gland with a tubuloacinar arrangement of poorly stained mucous cells (M). Small intralobular ducts (ID) are seen in connective tissue, as well as small fascicles of lingual striated muscle (SM) [Junquiera] LE 3 Trans 1 TG: Borneo, Lumawag, Malabag | Lerio, Ong Lo Page 7 of 8  APPENDIX LE 3 Trans 1 TG: Borneo, Lumawag, Malabag | Lerio, Ong Lo Page 8 of 8