Histology of Oral Cavity

University:
American Career College
Course:
MICR112 | General Microbiology
Academic year:

2020
Views:

86

Pages:

58
Author:

Callie Nielsen

Histology of Oral Cavity 1 Digestive System 2  Digestive system is composed of oral cavity, digestive canal and digestive glands  Oral cavity is composed of : lips, hard palatine , soft palate , tounge ,teeth, gingiva  Digestive canal is composed of: Esophagus, stomach, small and large intestine, rectum, and anus  Digestive glands are: salivary glands, liver, pancreas, gall bladder 4 Oral cavity 5 Oral Mucosa Oral mucosa composed of a stratified squamous epithelium (No keratinized) with underlying connective tissue 6 Lips External aspect is covered with skin  *Capillary loops close to surface  *Transition between nonkeratinized and keratinized epithelium  stratified squamous epithelium Lips External aspect(skin aspect) is covered with skin Vermillion zone is covered by thin skin without hair follicle and gland  *Capillary loops close to surface  *Transition between nonkeratinized and keratinized epithelium Internal aspect(mucosal aspect) is covered by wet stratified squamous epithelium Lip Lip Lip (external) Lip (external) Lip (Vermilion Border) Lip (Vermilion Border) 15 Hard Palate  Hard palate is immovable  Oral surface has masticatory mucosa composed of stratified squamous keratinized or parakeratinized epithelium with dense irregular connective tissue  Underlying bone supports soft tissues 16 Soft Palate  Oral surface has a stratified squamous nonkeratinized epithelium  Underlying dense irregular collagenous connective tissue may have skeletal muscles and mucous salivary glands 17 Tongue  Tongue is lined by stratified squamous nonkeratinized epithelium which is covering striated muscles and glands  Anterior part separated from posterior by a V-shaped groove; the sulcus terminalis  Anterior two third of upper(dorsal) surface of the tongue is rough and has 4 types of papillae  filiform, fungiform, foliate, circumvallate  Posterior part has lymphoid nodules and lingual tonsils 18 Dorsal Surface of the Tongue 19 Filiform Papillae – They are elongated, common all over tongue, have not any taste buds – Epithelium may be partly keratinized 20 Fungiform Papillae § Mushroom shaped § Epithelium is nonkeratinized § They have scattered taste buds on their dorsal aspect 21 Foliate Papillae They are located on posterolateral aspect of tongue Many taste buds present in lateral walls of ridges 22 Circumvallate Papillae  There are large circular structures on posterior surface of tongue  Deep groove around base of papillae  Many taste buds on sides of papillae 'I .I. /\J (a) �.&.,, 1..1....J J,. .&.V\.....1 ....,..., Four type of cells – Dark cells (type I ) – Light cells (type II) – Intermediate cells (type III) – Basal cells (type IV ) 29 Tooth & Tooth Support Tooth crown: enamel layer over dentin Tooth root: calcified cementum over dentin Tooth pulp: loose, gelatinous connective tissue Gingiva: oral epithelium with dense irregular connective tissue Periodontal ligament: dense connective tissue binding tooth to bone of socket Enamel Enamel overlies dentin of the crown; it is composed of 97% calcium hydroxyapatite, organic material and water Organic materials include of Enamelins and Amelogenins Enamel produced by ameloblasts Enamel formed as enamel rods Dentin Dentin forms the bulk of the tooth; composed of 70% calcium hydroxyapatite It is yellowish, and the second hardest substance of the body, produced by odontoblasts These cells are in pulp, but their process (odontoblastic process) occupy fluid filled spaces in dentin known as dentinal tubule Most of organic substance of detin is collagen type I Cementum It is overlies dentin of the roots; composed of 50% calcium hydroxyapatite Most of organic material is composed of collagen type I Cementoblasts produce cementum Periodontal ligament It is a dense irregular CT whose principal fiber groups are the main support of the tooth Most populous cells in PDL are fibroblasts Alveolar bone The alveolus is the bony socket in which the tooth suspended, It has three regions Alveolar bone proper, Spongiosa, and Cortical plate Tooth Pulp – Tooth pulp is a loose connective tissue with fibroblasts, collagen, ground substance, nerves, vessels but have not any adipocytes  In embryo, tooth pulp is mucous connective tissue Tooth Development Odontogenesis begins with the appearance of the dental lamina from oral epithelium Neural crest-derived ectomesenchyme surrounded dental lamina Odontogenesis passes through different stages mature tooth mature tooth, root mature tooth, Sharpey's fibers Gingiva fetal rat (early), developing tooth fetal rat, developing tooth fetal rat, developing tooth, dental papillae fetal rat, developing tooth, ameloblasts and odontoblasts fetal rat (mid), developing tooth fetal rat, developing tooth, enamel fetal rat, developing tooth, enamel fetal rat (late), developing tooth fetal rat, developing tooth fetal rat, developing tooth 52 Tooth formation begins in the embryo when ectodermal epithelium lining the oral cavity grows into the underlying mesenchyme of the developing jaws. At a series of sites corresponding to each future tooth, these epithelial cells proliferate extensively and become organized as enamel organs, each shaped like a wine glass with its stem initially still attached to the oral lining. Ameloblasts form from the innermost layer of cells in the enamel organ. Mesenchymal cells inside the concave portion of the enamel organ include neural crest cells that differentiate as the layer of odontoblasts with their apical ends in contact with the apical ends of the ameloblasts. Gingiva  Due to frictional forces of mastication its epithelium is keratinized or parakeratinized  Where it is attached to enamel surface it is stratified squamous nonkeratinized known as junctional epithelium  The 1-to 2-mm space between tooth and gingiva is gingival sulcus  Deep to epithelium is a dense irregular collagenous CT Pharynx Pharynx is a transitional zone between oral cavity and esophagus and trachea Pharynx have three portion: Oropharynx Nasopharynx Laryngopharynx Oropharynx is lined by stratified squamous nonkeratinized epithelium with submucosal glands