definition and general consideration 2
TRANSCRIPT
ORAL MUCOUS MEMBRANE
Ankur Tyagi
BDS 1st year
DEFINITION AND GENERAL CONSIDERATION
Epithelium Basement Membrane Lamina Propria Sub mucosa
Basic Structure Of The Oral Mucosa
EPITHELIUM Membranous tissue composed of one or more layers of cells
separated by very little intercellular substance and forming the covering of most internal and external surfaces of the
body and its organs.
SIMPLE SQUAMOUS EPITHLIUM Cells are so thin that
bulging are produced by nucleus
SIMPLE CUBOIDAL EPITHELIUM The length and breadth
of the cell are equal Nuclei are rounded
SIMPLE COLUMNAR EPITHELIUM The length of the cells
is much greater than their width
The nuclei are oval being elongated in the same direction as the cells
They lie near the bases of the cells
STRATIFIED SQUAMOUS EPITHELIUM (NON-
KERATINIZED) Only the most superficial
cell are squamous The cells in the basal layer
are columnar Middle layer are polyhedral Nuclei are oval in the basal
layer Rounded in the middle Transversely elongated in
the superficial layer
STRATIFIED SQUAMOUS EPITHELIUM
(KERATINIZED) The layers are the
same as that of non-keratinized
Has 1 addition layer on top of the flattened cells called keratin layer
EPITHELIUM
Oral mucous membrane resemble skin in many ways
Oral mucous membrane also has 2 layers Epithelium Connective tissue
Together called dermis It is also similar to intestinal mucosa because it has
Epithelium Lamina Propria Submucosa
EPITHELIUM However in the intestinal mucosa another layer is
present called Muscularis Mucosae This layer is present between the Lamina propria
and submucosa Epithelium in the skin is always orthokeratinized Oral mucosal epithelium may be
non-keratinized or keratinized
Keratinization is further divided into 2 types Orthokeratinized Parakeratinized
Differences Between
Keratinized oral mucosa Non Keratinized oral mucosa
Epithelium- Thickness is less
Layers- 4 layers of cells of distinct morphologies
Stratum Basale
Stratum Spinosum
Stratum Granulosum
Stratum Corneum
Thickness is more
Layers- 3 layers of cells of distinct morphologies
Stratum Basale
Stratum Intermedium
Stratum Superficialis
Classification On The Basis Of Degree Of Keratinization
Keratinized Oral Mucosa 1. Orthokeratinized oral mucosa – The epithelium whose surface
layer/squames stains bright pink and does not contain any nuclei. This layer is also called Cornified or Horny layer.
eg. Hard Palate , filiform papilla
2. Parakeratinized oral mucosa – The epithelium whose surface layer stains for keratin (eosinophilic) but shrunken/pyknotic nuclei are
retained in the surface layer. eg. Gingiva , transitional zone of lip
Non Keratinized Oral Mucosa eg. Lining mucosa- lip, cheek , vestibular fornix, soft palate ,
alveolar mucosa & floor of mouth
EPITHELIUM The content of dermis and lamina differ
considerable Skin appendages
Hair follicles Sebaceous glands Sweet glands
These are not seen in the lamina propria Likewise salivary glands are not seen in dermis Papillae of connective tissue protrude towards the
epithelium carrying blood vessels and nerves Epithelium is formed into ridges that protrude
BASEMENT MEMBRANE A complex arrangement links epithelium and
connective tissue components of oral mucosa
BASEMENT MEMBRANE
BASEMENT MEMBRANE This structure has 2 names
Basement Membrane
Basal Lamina
BASEMENT MEMBRANE Basement Membrane
Evident at light microscope level This zone is 1-4 um wide, relatively cell free Stains positive with acid-schiff method This means it has neutral mucopolysaccharides
BASAL LAMINA Basal Lamina
Evident at electron microscopic level and is epithelial in origin
Basal complex has lamina and fibers Basal lamina is made up of 2 layers
Lamina Lucida Lamina Densa
LAMINA LUCIDA This zone is called the clear zone This is present directly below the epithelial
cell layer This layer is 20-40 nm thick This layer has glycoprotein called laminin that
cements non-fibrillar type IV collagen in the lamina densa to epithelial cells
LAMINA DENSA Also knows as dark zone This is present beyond lamina lucida and
adjacent to connective tissue 20-120 nm thick Consists of type IV collagen coated on each
side by glycosaminoglycan heparan sulphate
BASAL LAMINA Thick collagen fibrils attach onto the lamina
densa with finer fibrils running through these to link the whole complex mechanically to connective tissue
Fibronectin has some time been found in the lamina densa and may play a role in adhering fibroblast and proteoglycans to it
Cells are attached to the basal lamina by hemidesmosomes
BASAL LAMINA
Basal lamina provide mechanical adhesion between oral epithelium and lamina propria
Acts as a molecular barrier and plays a role in response to tissue injury
Anchoring fibrils which contain type VII collagen form loops and are inserted into lamina densa
Collagen fibres of type I and II run through these loops