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SALIVARY GLANDS & TONGUE

PRE-LAB.#8BY PROF. ANSARIThursday, April 20, 2023.

Thursday, April 20, 2023

Objectives

• To distinguish the parotid salivary gland, sublingual and submandibular from each other histological.

• To study and differentiate the various papillae on the dorsum of tongue microscopically.

• To know the structure of a taste bud.

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The major salivary glands

• Parotid salivary gland is situated around the external ear.

• Sublingual salivary gland is located below the tongue.

• Submandibular salivary gland is situated in the digastrics triangle of neck.

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Parotid gland histological is a serous type

4A serous acinusA serous acinusThursday, April 20, 2023

The parenchyma of the parotid consists exclusively of serous cells

(no mucous cells).

• The parotid gland has structure and appearance similar to the pancreas.

• A serous cell's cytoplasm is bipolar .  The basal basophilia is due to a concentration of protein synthetic organelles (ribosomes on rough endoplasmic reticulum).  

• The eosinophilic zymogen granules are situated apically.

• Nuclei are round and basally situated. 5Thursday, April 20, 2023

A typical acinar cell is shaped like a pyramid..  Its basal surface, located at periphery of the acinus, rests on the basement membrane separating the acinus from the underlying stroma.  Its lateral surfaces (the sides of the pyramid) are attached to adjacent secretory cells.  Its apical surface is free and faces the acinar lumen, which communicates by duct with the outside.

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The duct system of salivary gland

• Acinus

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Intercalated duct(Simple cuboidal epithelium)

Striated duct(Simple Columnar epithelium)

Excretory duct(Stratified Cuboidal epithelium)

Main duct(Stratified squamous nonkeratinized)Thursday, April 20, 2023

Ducts of salivary glands

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Submandibular salivary gland

• It is predominantly serous gland, with few mucus acini.

• A serous acinus produces a watery saliva.

• A mucus acinus produces thick frothy enzyme rich saliva.

• A mixed acini have both type of saliva, a crescent shaped serous acinus is attached to mucus acinus, called as demilunes.

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10Compare the serous & mucus acini.

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Sublingual salivary glands

• This gland is predominantly mucus secreting gland.

• The mucus acinus is showing vacuolated/soap bubble appearance.

• The nuclei are flattened in shape and basally situated.

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Minor salivary glands

• Are distributed in the oral cavity, in the inner aspects of lips, cheek , tongue substance & palate.

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Tongue

• It is a muscular organ of deglutition, taste, salivation and speech.

• It shows papillae on dorsum of tongue.

• It is lined by stratified squamous non keratinized epithelium.

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Tongue dorsum

Thursday, April 20, 2023

Types of papillae

1. Filiform papillae

2. Fungi form papillae.3.Circumvallate

papillae.4. Foliate papillae.

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1.Threadlike. Smaller and much more numerous than the fungi form variety. Epithelial lining is keratinized stratified squamous and is devoid of taste buds.Thursday, April 20, 2023

Fungi form papillae2.Mushroom-like. Larger but much less frequent than Filiform papillae

• Has a stratified squamous non-cornified epithelial covering and a highly vascularized connective tissue core giving it a red hue in the living state.

• Although not seen here, the epithelium may contain taste buds.

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3.Circumvallate papillae

They line the V-shaped boundary between the anterior two thirds and posterior one third of the tongue.

• Stratified squamous epithelium covers the tongue surface and dips into the trenches between papillae.

• Trench is a moat or groove that surrounds each vallate papilla.

• Serous glands of von Ebner open in to the trench.

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4.Foliate papillae are not found in man

Found in Rabbit• The sides of the papilla

are straight and contain numerous taste buds that open into the furrow surrounding the papilla.

• The serous glands of von Ebner open into the base of the furrow to flush out taste provoking stimuli.

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• Skeletal muscle in the tongue is arranged in bundles which typically run at right angles to each other.

• Both longitudinally and transversely cut skeletal muscle fibers are present.

• In both section planes you can see that the nuclei are located in the periphery of the muscle fiber.

• Striations are visible in longitudinally cut fibers.

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Taste buds are the organs of taste. They are oval structures located in the lateral wall of vallate papillae and less frequently in the outer wall of

the trench

• It has a pore apically, through which microvilli protrude out.

• There are three types of cells in taste buds.

• Sensory cells, supporting cells & reserve cells.

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Applied anatomy

• Sjogren’s syndrome is a clinical syndrome where the salivary glands become dry.

• Mumps infection is a viral infection of parotid glands.

• Aglossia is a congenital absence of tongue.

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