Unit 13: Oral Mucosa and Buccopharyngeal Lymphatic Ring

Vocabulary flashcards covering the histology of the oral mucosa, layers of the digestive system organs, and specialized cell types in the oral cavity.

Tunica Mucosa

The layer next to the lumen, composed of epithelium, lamina propria (connective tissue), and the lamina muscularis (smooth muscle).

Meissner’s plexus

A submucosal ganglionic nerve plexus of the autonomic nervous system located in the tela submucosa.

Auerbach’s plexus

Also known as the myenteric plexus, this ganglionic nerve plexus is located between the inner circular and outer longitudinal layers of the tunica muscularis.

Tunica Serosa

The outermost tunic of the digestive tract, consisting of connective tissue covered by mesothelium; it is found in organs bordering the pleural, pericardial, and peritoneal cavities.

Tunica Adventitia

An outermost layer of connective tissue that lacks a mesothelium and blends with surrounding fascia, found in organs like the cervical part of the esophagus.

Dermis

Vascular dense connective tissue derived from mesoderm that contains papillae interdigitating with the epidermis.

Hypodermis

Also known as the subcutis, it is a layer of loose connective tissue containing fat that connects the skin to underlying tissues.

Masticatory Mucosa

Keratinized oral mucosa (orthokeratinized or parakeratinized) found on the gingiva and hard palate.

Lining Mucosa

Non-keratinized oral mucosa with a smooth interface that is flexible and tolerant of compression; located on lips, cheeks, floor of mouth, and soft palate.

Mucoperiosteum

A firm, inelastic attachment where the oral mucosa is joined directly to the periosteum of underlying bone without an intervening submucosa.

Parakeratinized Epithelium

A type of keratinized epithelium where the surface squames retain their pyknotic nuclei, indicating low cellular metabolism.

Stratum basale

The deepest layer of the epithelium composed of cuboidal or columnar cells that undergo mitosis and are connected to the basement membrane by hemidesmosomes.

Stratum spinosum

Also called the prickle layer, it consists of elliptical cells joined by desmosomes that appear as 'intercellular bridges' under a light microscope.

Stratum granulosum

A layer of larger flattened cells containing small basophilic granules called keratohyalin granules.

Stratum corneum

The cornified layer consist of large, flat, dead cells (squames) densely packed with keratin filaments and the matrix protein filaggrin.

Keratinocytes

Epithelial cells that synthesize keratin and cytokeratin, showing maturation as they migrate from the basal layer to desquamate at the surface.

Melanocytes

Basal layer cells derived from the neural crest that secrete melanin and transfer it to keratinocytes via dendritic processes.

Langerhans cells

Dendritic cells of hematopoietic origin found in the upper layers of the epithelium that function as macrophages and antigen-presenting cells ($CD1a$ positive).

Merkel cells

Neural pressure-sensitive receptor cells for touch sensation located among the basal cells, commonly found in masticatory mucosa.

Lamina propria

The connective tissue layer supporting the oral epithelium, divided into a superficial papillary layer and a deeper reticular layer.

Fordyce spots

Isolated sebaceous glands that may be present in the submucosa of the cheeks.

Vermilion zone

The transition zone of the lip between the skin and mucous membrane, characterized by thick keratinized epithelium and long papillae with large capillary loops.

Mucogingival junction

The anatomical boundary where the attached gingiva meets the alveolar mucosa.