Salivary Gland Histology & Function PDF

Salivary gland histology & function Dr Sandeep Gupta Oral Biology  STRUCTURE OF SALIVARY GLANDS Composed of (a) Epithelial (b) Connective tissue The epithelial component is called Parenchyma and it is supported by Connective Tissue....

Salivary gland histology & function Dr Sandeep Gupta Oral Biology  STRUCTURE OF SALIVARY GLANDS Composed of (a) Epithelial (b) Connective tissue The epithelial component is called Parenchyma and it is supported by Connective Tissue. 2  THE SECRETORY UNITS 1. Serous cells 2. Mucous cells 3. Myoepithelial cells THE DUCT SYSTEM 1. Intercalated ducts 2. Striated ducts 3. Terminal excretory ducts Terminal secretary units drains into ducts that is intercalated ducts striated ducts excretory ducts open into the oral cavity. 5  COMPONENT of Terminal secretory units SEROUS MUCOUS 6  1. Serous Cells/ Serous Acini Secretion of serous cells is thin, watery and proteinaceous. LIGHT MICROSCOPY Pyramidal in shape. Spherical nuclei are located basally. Numerous secretory granules in the apical Cytoplasm. 8-12 cells surrounding a central lumen. Cytoplasm  Intensely with H & E Nucleus  with hematoxylin 7 ELECTRON MICROSCOPY Serous cells  Protein secreting cell. Central lumen  lumen usually has finger like extension  located between adjacent cells called Intercellular Canaliculi. 8  Serous Cells/ Serous Acini Large amounts of RER placed Basally & laterally to the nucleus. Prominent Golgi complex located just apical or lateral to the nucleus. Apical cytoplasm filled with secretory granules. Secretory granules  +ve for PAS Stain 9 Apical cytoplasm of these cells shows accumulation of secretory granules 1µm in diameter Granules are zymogen granules Formed by glycolated protein which are released into a vacuole. 10  2. Mucous Cells/Mucous acini LIGHT MICROSCOPE Triangular or pyramidal in shape. Contain numerous granules containing mucins. Nucleus  Flattened & Basally placed. Cytoplasm  washed-out in routine H & E sections because organic solvents remove mucin. 11  Mucous Cells/Mucous acini Apical part  do not stain strongly with H & E higher carbohydrate content. Secretory material is strongly stained Mucicarmine Stain OR Alcian blue. 12  Lumen Nuclei 13 14  ELECTRON MICROSCOPE  Secretory material  Droplets.  Large golgi complex  located mainly basal to the mass of secretory granules.  Droplets are large than serous granules & irregular 15  Mucous Cells/Mucous acini  Nucleus  Oval or flat & just above BM.  RER & other cell organelles  less prominent  Intercellular Canaliculi seen.  Lumen larger than serous acinus. 16  3. Myoepithelial Cells:  Myoepithelial cells are contractile cells associated with the secretory end piece & intercalated duct.  Derived from epithelium.  Stellate shaped or spiderlike shape. 17  Myoepithelial Cells  Scanty perinuclear cytoplasm.  location : basal lamina and the secretory or duct cells.  Joined to the cells by desmosomes. 19  Myoepithelial Cells LIGHT MICROSCOPE  Only nuclei are visible in H&E stained sections. ELECTRON MICROSCOPY  Desmosomes B/W  secretory cells & Myoepithelial cells  provide structural stability. 20  Myoepithelial Cells  Cells  Basket cradling of secretory unit , hence the terms “ Basket Cells”.  “Octopus sitting on rock” 21  DUCTAL SYSTEM AND DUCTAL MODIFICATION  Ductal system production & modification of saliva  Contains 3 types of ducts o Intercalated duct o Straited duct o Terminal duct 22  INTERCALATED DUCTS (INTRALOBULAR) The intercalated ducts are lined by a single layer of low cuboidal cells. Contain a few secretory granules. Round/oval centrally placed nucleus. Empty-appearing cytoplasm. Small amount of RER is located in the basal cytoplasm. 23 24 25  STRAITED DUCTS (intralobular) Intercalated ducts pass into striated duct. Ducts lined by columnar cells. Central placed nucleus. Pale , acidophilic cytoplasm. 26  ELECTON MICROSCOPY  Most characteristic  Prominent striations at basal part of cells.  Numerous elongated mitochondria in narrow cytoplasmic.  Around the nucleus  Few rER, golgi complexes.  Luminal surface Microvilli  Desmosomal attachment. 27 28  Striated duct has a role in secretion and reabsoroption of water and electrolyte Striated border acts as sodium pumping machine Reabsorb sodium and chloride, secrete potassium and bicarbonate ions makes isotonic secretion to hypotonic secretion 29  TERMINAL EXCRETORY DUCTS ( interlobular )  They are located in connective tissue septa i.e. an extra lobular location.  They are larger in diameter than striated ducts.  Near striated duct  pseudostratified tall columnar cells admixed with small basal cells & goblet cells.  Tall columnar stratified squamous merges with oral epithelium at duct orifice. 30 Excretory ducts with pseudostratified or stratified epithelia 31  Lingual glands Anterior lingual glands: Blandin –Nuhn (tip of tongue, ventral surface, lingual frenum) Posterior lingual glands: 1. Von Ebner gland 2. Weber gland 32  Von Ebner gland Location: between muscle fibres, below the circumvallate and foliate papillae, purely serous gland. Function 1.washing out the trough of papillae and ready the taste receptors for a new taste stimulus 2. as secretion contains antibacterial and lipolytic enzyme(digestion of fat in newborn, more in animals rather than human) it has protective and digestive enzymes 33 Von Ebner gland 34  WEBER GLANDS Location: posterior one third of tongue, post to sulcus terminalis in association with lingual tonsils Duct :dorsal surface of tongue through the lingual crypts 35  Composition of saliva 99 % of water and 1 % of organic and inorganic substances Organic substance: protein in nature include enzymes, mucins and antibacterial substances,(minor quantity of albumin, blood clotting factor and immunoglobulin IgA) Inorganic substances: sodium , chloride, bicarbonate and less quantity of calcium, magnesium, phosphate, iodine, thiocyanate, and fluoride. 36  Volume Majority is secreted by submandibular gland followed by parotid and sublingual gland Least amount by minor salivary glands 37  Functions of Saliva 1. Digestion of food: Aamylase-carbogydrate into glucose and maltose Lingual lipase: secreted by Von Ebner’s gland –fat digestion Preparation of food for swallowing 2. The oral tissue moist and lubricated 3. Role in speech 4. Temperature regulation in animals 5. Protection against caries: buffering the acid produced by bacteria 38  Functions of Saliva 6) Protection by antibacterial factors in saliva Peroxidase (acinar cells)and thiocynate (duct system)inhibit the growth of microorganism Lysozyme Immunoglobulins Lactoferrin Histidine(acts on fungus as well as bacteria) 7) Taste sensation 8) Tissue repair(epidermal growth factor) 39 Thank You