Histology of Oral Mucosa Flashcards

Comprehensive vocabulary flashcards covering the components, cell layers, regional variations, and glandular histology of the oral mucosa based on the DS1101 lecture.

Basement Membrane

A layer $1–2\text{ microns}$ thick that links the oral epithelium to the underlying connective tissue.

Lamina Propria

The sub-epithelial connective tissue consisting of a papillary layer and a reticular layer.

Submucosa

A loose fatty glandular tissue layer containing vessels and nerves, present in the cheeks, lips, and parts of the hard palate.

Lamina lucida

A layer within the basement membrane that is $20–40\text{ nm}$ thick and located immediately under the epithelium.

Lamina densa

An electron dense part of the basal lamina composed of a type IV collagen network.

Oral Mucoperiosteum

Mucosa directly attached to bone, characterized as firm and inelastic; present in the gingiva and parts of the hard palate.

Keratin

A family of fibrous structural proteins providing mechanical protection to the oral mucosa, also found in skin, hair, and nails.

Stratum basale (Basal Layer)

A single layer of cuboidal or columnar cells adjacent to the lamina propria; the site of mitosis containing stem cells and replacement keratinocytes.

Stratum spinosum (Prickle / Spinous Layer)

A layer of elliptical or spherical cells where desmosomes give a prickly appearance and tonofibrils are present.

Stratum granulosum (Granular Layer)

A layer consisting of $3–5$ layers of flattened cells containing keratohyaline granules, which house the protein filaggrin.

Stratum corneum

The most superficial layer of keratinized epithelium consisting of flat squames with no nuclei or organelles, filled with keratin and shed continuously.

Orthokeratinized

Complete keratinization where there are no nuclei or organelles in the surface layer; typical of the hard palate.

Parakeratinized

A type of keratinization where nuclei are retained but appear small and shrunken; commonly seen in the gingiva.

Desmosomes

Cell-to-cell junctions providing strong adhesion via intermediate filaments ($10\text{ nm}$) to resist mechanical stress.

Hemidesmosomes

Junctions that attach keratinocytes to the extracellular matrix or basal lamina via intermediate filaments.

Adherens Junctions

Intermediate junctions for cell-cell and cell-matrix adhesion involving actin filaments ($7\text{ nm}$).

Gap Junctions

Communicating junctions that allow direct chemical communication between adjacent cells through specialized proteins.

Tight Junctions

Multiprotein complexes that prevent the leakage of solutes and water between epithelial cells.

Melanocytes

Non-keratinocyte cells derived from neural crest cells located in the basal layer; they produce melanin packed into melanosomes.

Langerhans cells

Dendritic immune cells from bone marrow precursors located above the basal layer; involved in contact hypersensitivity and anti-tumour immunity.

Merkel cells

Specialized pressure-sensitive touch receptors in the basal layer, most common in masticatory mucosa, associated with nerve fibres.

Masticatory Mucosa

The type of oral mucosa found in the gingiva and hard palate, designed to withstand the friction of chewing.

Lining Mucosa

Flexible and moist mucosa found in the lips, buccal mucosa, floor of the mouth, ventral tongue, soft palate, and alveolar mucosa.

Fordyce's spots

Sebaceous glands that may be visible in the buccal mucosa (cheek).

Vermilion Zone

The transitional zone of the lip between keratinized skin and non-keratinized mucosa, characterized by capillary loops close to the surface and a red/pink colour.

Filiform Papillae

The most numerous, thin, cone-shaped papillae on the anterior $2/3$ of the tongue; they lack taste buds and provide texture and touch sensation.

Circumvallate Papillae

Large papillae anterior to the sulcus terminalis surrounded by a trench; contain taste buds and receive amylase secretions from von Ebner's glands.

Taste Buds

Barrel-shaped chemoreceptive organs containing supporting cells and gustatory cells that detect salty, sour, bitter, sweet, and umami tastes.

Striated duct

A duct in the salivary gland system characterized by infolded basolateral membranes for ion transport, leading to the collecting duct.

Serous acinar cells

Wedge-shaped secretory cells with basal nuclei and dense granules that stain deeply with H&E.

Mucous acinar cells

Triangular or pyramidal secretory cells with flattened nuclei and numerous mucin granules that appear pale under H&E.

Serous demilunes

Half-moon shaped groups of serous cells located at the distal end of mucous secretory units that secrete lysozyme.

Myoepithelial cells

Branched stellate cells that wrap around acini and ducts to squeeze out secretions.

Parotid Gland

The largest major salivary gland, producing purely serous (with occasional mucous) secretions.

Submandibular Gland

The second largest major salivary gland, characterized by mixed sero-mucinous secretions.

Sublingual Gland

A major salivary gland that is predominantly mucous, lacks striated ducts, and produces sodium-rich saliva.

Xerostomia

A clinical condition of dry mouth resulting from reduced salivary gland function.

Hyperkeratosis

Excessive production of keratin that appears as white patches on the oral mucosa, also known as leukoplakia.