Parotid serous, sublingual mucous, submandibular mixed
Expansion
| Gland | Acinar type | Distinguishing feature |
|---|---|---|
| Parotid | Purely serous | Adipose tissue within the gland; the facial nerve passes through |
| Submandibular | Mixed, mostly serous | Serous demilunes capping mucous acini |
| Sublingual | Mostly mucous | Few serous cells |
Serous cells: pyramidal, basophilic cytoplasm from abundant rough endoplasmic reticulum, round central nuclei, apical zymogen granules. Produce watery, enzyme-rich secretion.
Mucous cells: pale, foamy, flattened basal nuclei, since mucin does not stain with H and E.
Ducts: intercalated, then striated (with basal infoldings and mitochondria giving the striations, and modifying electrolytes to make saliva hypotonic), then excretory.
Myoepithelial cells surround acini and expel secretion.
Clinical correlations: the parotid is the commonest site of salivary tumours, of which about 80 per cent are pleomorphic adenomas; Sjogren syndrome shows lymphocytic infiltration and acinar destruction; and mumps causes parotitis. Stones are commonest in the submandibular gland, because its secretion is more viscid and its duct runs upwards.