Practice 2 Major salivary glands TMJ, Methods Structure of salivar glands Ligaments – capsule, septa, connective tissue Parenchyma – lobules - secretory compartments: serous acins, mucinous tubules or tubules with Gianuzzi lunules - ducts: intercalated and striated ducts (interlobular and main in v septa between lobules) Serous acini BM, myoepithelial and serous cells Mucinous tubules BM, myoepithelial and mucinous cells Tubules with Gianuzzi demilunes Myoepithelial cells • Ectomesenchymal origin • Contraction • Desmosomes • Vegetative control Salivary ducts types – Intercelual (they do not have their own wall, intercellular space) – Intercalated (simple squamous ep., only serous and mixed glands) – Striated (simple cuboidal/low columnar ep.; basal labyrinth striation) – Interlobular (simple – stratified columnar ep., in septs) – Main (stratified columnar ep.) Ducts Intercalated StriatedIntercellular Main Interlobular Intercalated ducts Narrow and thin-walled channel, collapsed on slides Wall: basal membrame, myoepithelial cells and simple squamouse to low cubic ep. Numerous in serous type of glands (cells of intercalated ducts secrete to saliva macromolecular substances: lysozym + lactoferin) Striated ducts Wider than the intercalated ducts (easy to find), usually in the middle of lobe Wall: Basal membrane and simple cuboidal/low columnar ep. Microvilli on apexes and an bases characteristic striation (basolateral labyrinth) In the cytoplasm of cytokeratin filaments The cells of striated ducts regulate the content of water and electrolytes (Na+, K+, Cl-, Ca2+, Mg2+, HCO3-) in the secretion. Resorption of Na+, and ClSecretion of K+ and HCO3nerve control Striated duct – basal labyrinth Base of epithelial cell: Invagintion of cytoplasmic membrane, numerous mitochondria Epithelial cell Main ducts Stratified columnar ep. with goblet cells Ductus parotideus Ductus submandibularis Ductus sublinguales (major et minores) Interlobular and main ducts Interlobular ducts Located in fibrous septae between the lobes (columnar or stratified columnar epithelium) They are formed by the connection of several striated ducts Lined by a high single-layer columnar and in the terminal sections also a stratified columnar epithelium Main ducts Stratified columnar ep. In epithelium Goblet cells Wall supported by the dense collagenous connective tissue and smooth muscle cells Striated ductIntercalated duct Sialendescopy Glandula parotis • SEROUS gland • 14 - 28 g • capsule, septs and lobules • Serous acini, ducts: long intercalated ducts, numerous of striated ducts • ductus parotideus (Stenoni) - 2. upper molar (Steno/Stensen, Niels) • adipocytes Glandula submandibularis • MIXED tuboalveolar gland, predominantly SEROUS • 10-15 g • serous acini - 80 %, rest are mucinous tubules with Gianuzzi demilunes • intercalated and striated ducts • ductus submandibularis (Whartoni) - frenulum linguae trigonum submandibulare Glandula sublingualis • MIXED tuboalveolar gland, predominantly MUCOUS • 2g • located on the floor of the mouth on mylohyoid muscle near the midline • Mucinous tubules, serous acini are rare, instead of them: Gianuzzi demilunes • Intercalated ducts are missing, striated ducta are present, but are reduced in number and short • ductus sublingualis major (Bartholini) • ductus sublinguales minores (Rivini) along the crest of the plica sublingualis gl. sublingualis gl. apicis lingue smíšená, přev. mucinózní Location Name Type Size Lips gll. labiales sup. et inf. mixed, pred. mucinous minor Cheeks gll. buccales mixed, pred. mucinous minor gll. molares (retromolares) mixed, pred. mucinous minor GL. PAROTIS serous MAJOR Palate hard gll. palatinae (glandular zone) mucinous minor soft gll. palatinae mucinous minor Tongue Apex gl. apicis lingue (Blandini-Nuhni) mixed, pred. mucinous minor/ major Terminal sulcus gll. Ebner‘s (gll. papillae vallatae) serous minor Base gll. Weber‘s (gll. linguales post.) mucinous minor Floor of the mouth GL. SUBMANDIBULARIS mixed, pred. serous MAJOR GL. SUBLINGUALIS mixed, pred. mucinous MAJOR Comparison of the hard tooth tissues (and lamellar bone) Enamel Dentin Cementum Lamellar bone Colour White (to light blue) Ivory Brown-yellow Brown-yellow Inorganic (%) Organic (%) H20 (%) 96 (86) 1 (2) 3 (11) 70 (45) 20 (30) 10 (25) 61 (33) 27 (31) 12 (36) 45 (23) 30 (37) 25 (40) Collagen fibres NO YES (perpendicular to the dentinal tubules) YES (in all directions) YES (same direction in lamellas) Cells Ameloblasts (missing in adults) Odontoblasts (on the pulpal side of dentin) Cementoblasts (cementocytes) Osteoblasts osteocytes Blood vessels NO NO NO YES (in Haversian canals) Nerves NO YES (on entry of dentinal tubules) NO YES (in Haversian canals) Procedures used to study the microscopic structure of teeth 2 basic methods of hard tissue processing are used in light microscopy: 1. Ground sections 2. Decalcified samples (and staining) 1. Ground sections 50 - 70 µm discs made by grinding (saw, carborundum wheel, fine grinders, abrasive powders and pastes during grinding, the disc must be water-cooled, the finished cut is sealed in a Canadian balm, which heats up when mounted above the flame - so all the cavities and channels are preserved in the cut-out The preparation of the cut-out requires great skill) 2. Stained sections of decalcified tooth Long preparation: decalcification of the tooth, embedding, staining Decalcification: dacalcification agents convert insoluble calcium salts (phosphate and carbonate) to water-soluble salts. The time required for descaling depends on the size of the object and the type of decalcifying fluid: from several days to weeks and months Decalcification agents:  Acids (e.g. 5% nitric acid, 5% trichloroacetic acid and 22-23% formic acid) - 1 week  Chelating agents – EDTA: 4 weeks - 3 months preserves well the structure of the tissue and enable the staining Embedding – paraffin, resins Sectioning – cryotome, microtome (decalcified); staining Stained slice of dacalcified tooth ! Soft tissues are not preserved on ground sections Enamel is missing on decalcified teeth Tooth - root Predentin odontoblasts Cementum Periodontium Dentin Pulp Gingiva libera (1) Gingiva affixa (2) Sulcus gingivalis 1 2 Dentin, SEM, 1 500x Dentin, SEM, 1 500x Samples gl. parotis 8 gl. submandibularis 9 gl. sublingualis 10 gl. apicis linguae 2