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Salivary Glands (Purely Exocrine Secretory Organs) - Coggle Diagram
Salivary Glands (Purely Exocrine Secretory Organs)
Embryology & Exocrine Classification (Ectoderm vs Endoderm; 4 Criteria)
Major Salivary Glands (Ectodermal / Epiblast)
Sublingual Primordia
8th week
of gestation
Parotid Primordia
7th week
of gestation
Submandibular Primordia
6th week
of gestation
Accessory Glands (Endodermal)
Microscopic mucosal units
Classification Tiers of Exocrine Glands
Exocrine glands are categorized according to four fundamental histological criteria:
Mode of Secretion
Merocrine
Secretion released via simple exocytosis without cell membrane loss (e.g., salivary glands, pancreas)
Holocrine
Whole cell disintegrates to form the secretion (e.g., sebaceous glands)
Apocrine
Secretory product released along with a portion of apical cytoplasm (e.g., mammary glands)
Nature of Secretion
Serous: Watery, protein/enzyme-rich fluid
Mucous: Viscous, glycoprotein-rich (mucin) fluid
Mixed (Seromucous): Contains both serous and mucous secretory cells
Duct Architecture
Simple Glands: Possess an unbranched excretory duct
Compound (Composite) Glands: Possess a branched duct tree system
Secretory Unit Morphology
Tubular, Acinar (Acinous), or Alveolar (or combinations like tubuloacinar)
Major Salivary Glands (3 Paired Anatomical Organs)
Parotid Gland
Excretory Path: Drains via Stensen's Duct, traversing the buccinator to open into the vestibule opposite the upper second molar
Size & Weight: Largest salivary gland (25 g); pyramidal shape with a lobulated yellowish appearance
Submandibular (Submaxillary) Gland
Excretory Path: Drains via Wharton's Duct, terminating at the sublingual papilla adjacent to the lingual frenulum
Size & Weight: Almond-sized (7 g); located beneath the mandibular angle
Sublingual Gland
Excretory Path: Multiple small ducts, the largest being the Duct of Rivinus (Bartholin's duct), which frequently empties into Wharton's duct
Location & Structure: Floor of the mouth; elongated, flattened aggregate of small glandular lobules
Accessory Salivary Glands (Microscopic Mucosal Clusters)
Location & Size
Microscopic (1–3 mm) embedded in lamina propria
Distribution: Hundreds of microscopic (1-3 mm) glands scattered within the mucosa/lamina propria across the buccal, labial, lingual, palatine, and pharyngeal regions
Function: Maintain continuous basal moisture and lubrication independent of gustatory stimulation
Specialized Example
Von Ebner's Glands
Purely serous glands associated with the circumvallate papillae of the tongue
Secrete lingual lipase and fluid to cleanse the gustatory grooves surrounding taste buds