Salivary Glands and Lymphoid Tissue in the Oral Cavity PDF

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Summary

Salivary glands and lymphoid tissue and how they work together in the oral cavity...

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BIO4328

DH 02

Winter 2018

Prepared by Maria Tigner

Salivary Glands and Lymphoid Tissue related to Oral Cavity Glands – a subdivision of epithelium specialized on synthesizing compounds. Glands secrete  

Through ducts – these are exocrine glands, maintain a duct which opens in the epithelial surface Directly into the blood stream by diffusion, these are endocrine cells, losing the duct that connects to an epithelial surface; secretions pass through the endothelial lining of blood vessels to enter the blood stream.

Embryonic development Both types of glands develop embryonically to become endocrine or exocrine. In certain places the epithelium in the early embryo grows downward into the underlying CT., much more like the tooth germ develops, with a downward growth invading the CT. As the epithelial cells multiply, they modify and become specialized. Salivary glands They are specialized exocrine glands in which some epithelium develops in secretory cells and some into ducts of the gland. The secretory cells produce saliva. Secretory cells There are two types, serous and mucous, saliva glands are made up serous cells, mucous cells or a combination known as seromucous. Structural elements of salivary glands A CT capsule, extending as sheets into the gland dividing the gland into lobes and further into lobules; it bears the ducts, blood vessels, lymphatics and nerves of the gland. The ducts of the gland divide into smaller and smaller branches ending with the secretory portion. Exocrine glands Are classified according to the composition of their secretions and the method by which secretion occurs: 

Merocrine glands – secrete watery protein rich fluids by exocytosis without compromising the integrity of the gland cells.



Apocrine glands - cells of the gland loose small portions of the cytoplasm as fluid-filled packets 1

BIO4328



DH 02

Winter 2018

Prepared by Maria Tigner

Holocrine glands – the entire cell lyses during secretion

Most exocrine secretory glands are merocrine, and can be further subdivided into  Serous cells – typically watery with high concentration of enzymes, called serous fluid  Mucous cells – secretion of mucous cells is thicker, rich in glycoprotein mucin called mucous SUMMARY OF GLANDULAR SECRETION Secretory type Merocrine gland

Description of secretion A fluid released by exocytosis

Example Salivary glands, pancreatic glands, certain sweat glands

Apocrine gland

Cellular product and portions of free ends of glandular cells pinched off during secretion

Mammary glands, certain sweat glands which are active with emotions

Holocrine gland

Entire cells that are filled with secretory products

Sebaceous glands (oil glands of the skin)

Label the type of gland with its diagram – choose from apocrine, merocrine and holocrine

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BIO4328

DH 02

Winter 2018

Prepared by Maria Tigner

Match the type of gland to its description 1. Secretes a fluid product released by exocytosis_____

A. Apocrine

2. Entire cells are filled with secretory product______

B. Merocrine

3. Cellular product and portions of the free ends of cells pinched off during secretion_____

C. Holocrine

Parotid Glands They are major salivary glands which secrete pure serous saliva, largest salivary glands located in front of the ear and the deeper parts fill a fossa (space) near the mandible. The main duct, Stensen’s duct, opens into the oral cavity on the mucosa of the check opposite to right and left maxillary 2nd molars. Submandibular glands Are located below and central the angle of the mandible. The main secretory duct, Wharton’s duct, opens by a narrow orifice on either side of the lingual frenum on the floor of the mouth. The submandibular gland is mixed, and predominantly serous. Sublingual glands They are located on the floor of the mouth. They are a composite of one large and several smaller glands. The main duct opens into the oral cavity near the duct of the submandibular glands. The ducts of the smaller sublingual glands number between 8 and 20 and open independently on the floor of the mouth. The sublingual gland is of a mixed type, muco-serous gland predominantly mucous. Minor salivary glands They are located:     

Inner surface of the lips – labial glands – mixed glands (serous-mucous secretions) Buccal glands inside the cheek – buccal glands – mixed glands too Soft palate, center of the hard palate – palatine glands – pure mucous glands Tonsillar folds – glossopalatine glands – pure mucous glands Glands of the tongue (taste buds) o called Von Ebner’s glands – watery secretions to wash out the taste buds of circumvallate papillae – serous glands o Also on the tip of the tongue – mixed glands

Each minor gland is small, consisting of a cluster of acini, and each is drained by a short duct. 3

BIO4328

DH 02

Winter 2018

Prepared by Maria Tigner

The average individual produces approximately 1.5 litres of saliva a day. Amount of saliva secreted each day – 1.5 litres. Clinical comments related to saliva Saliva serves many functions, ranging from a solvent to assist mastication of food, digestion of carbohydrates, moistens food and oral tissues, cleanses the mouth and inhibits the growth of some bacteria. Within the components of saliva, there are calcium and phosphate ions which increases enamel surface hardness of newly erupted teeth and assist in enamel re-mineralization. Pharmacology implications – certain drugs like antihistamines, tranquilizers, and barbiturates decrease salivary flow resulting in dry mouth with significant implication for oral health. Structure of salivary glands The functional unit is known as the acinus or alveolus – epithelial cells. The collecting duct or secretory end piece or intercalated duct – epithelial cells. Review questions – please note the answers to the review questions are responsibility of the students, the professor will not provide the answers. A. Indicate whether each of the following parts of a salivary gland is formed of epithelial or CT. 4. Duct of the gland_____ a) epithelial tissue 5. Vascularized tissue of the gland_____ b) connective tissue 6. Secretory cells of the gland______ B. Match the salivary gland with its anatomical description. Each option can be selected once, or more than once or not at all. 7. Located below the ear _____ 8. Located below the posterior part of the tongue ____ 9. Located in the anterior part of the floor of the mouth____ 10. Drained by Wharton’s duct____ 11. Drained by Stensen’s duct____ 12. Drained by Wharton’s duct and several other small ducts____ 13. Located in the posterior part of the tongue___

a) b) c) d)

Parotid gland Sublingual gland Submandibular gland Von Ebner’s gland

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BIO4328

DH 02

Winter 2018

Prepared by Maria Tigner

C. Describe three areas besides the tongue where minor salivary glands can be found. 1. ________________________________________ 2. ________________________________________ 3. ________________________________________ D. List six functions of saliva. 1. ____________________________________________ 2. ____________________________________________ 3. ____________________________________________ 4. ____________________________________________ 5. ____________________________________________ 6. ____________________________________________ TONSILLAR TISSUE RELATED TO ORAL CAVITY Tonsillar tissue Surrounds the oropharynx in a ring called Waldeyer’s ring, the locations of the different tonsillar tissue, maximize the protection of oral cavity. These tissue – organs are positioned strategically at the entrance of the alimentary canal by the oropharynx. Their function is to produce lymphocytes and with the help of macrophages, protect the individual against foreign cells, microbes and cancer cells. The lymphocytes produced by the tonsils are able to recognize foreign intruders and cells and respond by transforming in T cells aiming to destroy foreign cells directly, or by forming B cells, plasma cells to secrete antibodies. Classification of tonsillar tissue  Pharyngeal tonsil or adenoid – single tonsil located in oropharyngeal midline  Bilateral palatine tonsils – bilaterally located adjacent to the most posterior molars 

Bilateral lingual tonsils – bilaterally located in the floor of the mouth

There may also be some lymphoid tissue in the lateral most posterior portion of the tongue. Tonsils are part of the lymphatic system which also includes lymph nodes, thymus, spleen, and diffuse lymphatic tissue.

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BIO4328

DH 02

Winter 2018

Prepared by Maria Tigner

ref: http://www.entconsultant.co.uk

References • • • • • • •

Bath-Balogh and Fehrenbach. Illustrated dental embryology, histology, and anatomy. 3rd ed. Elsevier Saunders. Orban’s oral histopathology. 11th ed. St. Louis, 1991. Mosby Oral histology and embryology supplemental notes. Algonquin College. BIO 4328. Winter 2013 Melfi and Alley. Permar’s oral embryology and microscopic anatomy. 10th ed. LW&W Avery and Chiego, Essentials of Oral Histopathology and Embryology. 3rd ed., 2006 Berkovitz, Holland & Moxham. Oral anatomy, histology and embryology. 4th ed. Mosby Elsevier. Nanci A. Ten Cate’s Oral Histology, 7th ed. Mosby, St. Louis, 200

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