Oral Cavity Histology Histology > Digestive System > Digestive System 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) Powered by TCPDF (www.tcpdf.org) 3 / 3.