Oral Cavity Histology Histology > Digestive System > Digestive System

Home , Lingual papillae, Lingual tonsils, Serous demilune, Sublingual gland

Oral Cavity LINGUAL PAPILLAE OF THE TONGUE

Lingual papillae cover 2/3rds of its anterior surface; lingual tonsils cover its posterior surface.

There are three types of lingual papillae:

- Filiform, fungiform, and circumvallate; a 4th type, called foliate papillae, are rudimentary in humans.

- Surface comprises stratified squamous epithelia

- Core comprises lamina propria (connective tissue and vasculature)

- Skeletal muscle lies deep to submucosa; skeletal muscle fibers run in multiple directions, allowing the tongue to move freely.

- Taste buds lie within furrows or clefts between papillae; each taste bud comprises precursor, immature, and mature taste receptor cells and opens to the furrow via a taste pore.

Distinguishing Features: Filiform papillae

• Most numerous papillae

• Their role is to provide a rough surface that aids in chewing via their keratinized, stratified squamous epithelia, which forms characteristic spikes.

• They do not have taste buds.

Fungiform papillae

• "Fungi" refers to its rounded, mushroom-like surface, which is covered by stratified squamous epithelium.

Circumvallate papillae

• Are also rounded, but much larger and more bulbous.

• On either side of the circumvallate papillae are wide clefts, aka, furrows or trenches; though not visible in our sample, serous Ebner's glands open into these spaces.

DENTITION

Comprise layers of calcified tissues surrounding a cavity that houses neurovascular structures.

Key Features Regions

1 / 3 • The crown, which lies above the gums

• The neck, the constricted area

• The root, which lies within the alveoli (aka, sockets) of the jaw bones.

• Pulp cavity lies in the center of the tooth, and extends into the root as the root canal.

• Neurovascular structures pass through the apical foramen to reach the pulp cavity.

Layers

• Dentin: comprises calcified organic matrix and inorganic hydroxyapatite crystals; this makes the dentin similar to, but harder than, bone.

• Cementum: covers dentin in the neck and root regions; is anchored to the surrounding periodontal membrane by ligaments (not shown, here).

• Enamel: covers the crown of the tooth; it comprises enamel rods (aka, prisms), and is the hardest material in the body.

Bony attachments

• Sockets = alveoli

• The periodontal membrane (aka, ligament) lies between the tooth and the bone

• Gingiva epithelium covers bone (gingiva refers to the gums)

- Gingival sulcus is the small space between the gingiva and the neck of the tooth. This space is enlarged in periodontal disease.

SALIVARY GLANDS

• Comprise acini that secrete watery and/or mucous solutions with digestive enzymes.

- These secretions are forced from the acini lumen, through intercalated and striated ducts, and, ultimately, into the oral cavity via main salivary ducts.

• Myoepithelial cells encircle acini; these cells wrap around serous and mucous acini, and contract to force their secretions from the acini lumen into the ductile system.

• Striated ducts receive secretions from intercalated ducts; these are distinguished by their striped appearance, which derives from basal interdigitations of cytoplasmic processes.

Parotid Gland

• Lies in the cheek and is the largest salivary gland

• Septum = ribbons of connective tissue that divide the glandular tissue into irregular-shaped lobes.

- House blood vessels and large excretory ducts, which are characterized by stratified cuboidal epithelia.

• The lobular tissue = serous acini, which are clusters of cells that produce a watery substance.

- At higher magnification, we would see the cytoplasmic zymogen granules that contain digestive enzymes and proenzymes.

2 / 3 Sublingual gland

• Lies under the tongue.

• Comprises light-staining mucous acini, which appear cloud-like in this sample.

- Adipocytes may also be present; they are more prevalent in the glands of older individuals.

Submandibular gland

• Lies under the lower jaw bone (the mandible)

• Comprises a mix of light and dark acini

- Mucous acini with serous demilune caps

Images: Histology (Mark Braun, MD, & Indiana University: http://medsci.indiana.edu/c602web/602/c602web/toc.htm; http://www.indiana.edu/~anat215/virtualscope2/start.htm)