HISTOLOGY OF SALIVARY GLANDS Dr. Sobia Ibrahim Assistant Professor Anatomy, KEMU

Saliva is produced by Three major salivary glands Parotid Submandibular Sublingual Numerous minor salivary glands

Saliva is a hypotonic watery secretion It contains mucous, Enzymes, Secretory antibodies, Inorganic salts. Daily production is ml in human

GENERAL STRUCTURE OF SALIVARY GLANDS  STROMA  Capsule  Septa  Blood vessels & nerves  Ducts  Lobule  PARENCHYMA  Accini  Duct system

Each gland is surrounded by a connective tissue capsule From capsules, multiple septae are thrown inwards to divide the parenchyma into incomplete lobules Within each lobule many secretory acini are surrounded by fine loose C.T. Blood vessels, lymphatic vessels, nerves and excretory ducts travel through septa.

PARENCHYMA Glands are tubuloacinar variety Acini consists of secretory cells which have a lumen in middle going to duct Serous, mucous or mix. Myoepithelial cells lie between plasmalemma and basal lamina of secretory cells

MUCOUS & SEROUS ACCINI

DUCT SYSTEM  INTERCALATED DUCTS  Lined by cuboidal epithelium  STRIATED DUCT  Lined by columnar cells & show Radial striations  INTERLOBULAR/  EXCRETORY DUCTS- in CT septa  Proximally- pseudostratified/stratified cuboidal  Distally – stratified columnar  MAIN DUCT  Non keratinized stratified squamous epithelium

PAROTID GLAND  BRANCHED ACCINAR gland  SEROUS  Striated & intercalated ducts in parenchyma  Interlobular duct in CT septa  Plasma cells present in CT septa  Secretory products has:  Amylase  Proline- rich protien which has calcium binding properties

SUBMANDIBULAR GLAND  BRANCHED TUBULOACCINAR gland  Predominantly SEROUS  Majority serous accini  Mucous accini with serous demilunes-10%  Well developed striated ducts  Underdeveloped intercalated ducts  Secretory products have:  Amylase  Proline rich protiens  Lysozymes

SUBLINGUAL GLAND  BRANCHED TUBULOACCINAR gland  Predominantly mucous  Serous cells only as demilunes  Striated & intercalated ducts not well developed  Secretory products :  Amylase  Lysozymes

COMPARISON

MINOR SALIVARY GLANDS Scattered throughout oral mucosa & submucosa Nonencapsulated Usually MUCOUS Exception is von Ebner gland of tongue Short ducts open on oral mucosa B lynmphocytes releasing IgA common

MEDICAL APPLICATION Reduced function of major salivary glands due to disease / radiotherapy RESULTS: ◦ Caries ◦ Atrophy of oral mucosa ◦ Speech difficulties

SEROUS CELL Pyramidal cells. Broad end facing the basement membrane and narrow end facing lumen. 6-8 in no. Apex has microvilli Basal region has rounded nucleus. Basal region have abundant RER (due to which basal region stain basophilic)and mitochondria. Apical region : zymogen (secretory) granules,so apical region is acidophilic Adjacent serous cell joined by junction near apices. Intercellular canaliculi FUNCTION: thin and watery secretions

MUCOUS CELL Tall cuboidal or low columnar cells with basal flattened nuclei. Apical region has mucinogen granules. H&E stain mucous poorly so muous cells appear empty. Well developed golgi apparatus. E/M: junctional complexes, no intercellular canaliculi. Cells secrete mucinogen which on contact with water form mucous.