For the study of the major salivary glands, examine sections of the parotid gland (slide 132) and the submandibular gland (slide 11 and 72).

Such a gland is shown schematically in Fig. 16-2 and in this diagram, which also shows the comparison with the pancreas which is histologically very similar to the major salivary glands. Click the image for an expanded view.

• Acini of the parotid gland (Fig. 16-3) are completely serous.
• Submandibular gland (Fig. 16-6) are mixed serous and mucous.
• The PAS -alcian blue stain of slide 11 stains mucus well and shows distinct difference between the types of secretory cells.
• Compare serous and mucous secretory cells in these slides.
• On slides 72 and 11, identify the mucous and serous cells and look for serous demilunes (Fig. 16-6).

What do serous and mucous cells respectively contribute to saliva?

What could be the functional significance of serous demilunes?

Clinical note: The childhood disease called mumps is a viral infection of the salivary glands, almost always the parotid glands, causing swelling and tenderness for a week or so. The disease is usually self-limiting but the virus can spread to other organs, including the inner ear where it can lead to deafness.

Look for striated ducts (Fig. 16-5) and larger excretory ducts in both slides 11 and 132.

What unusual types of epithelia are found in the ducts of salivary glands?

What accounts for the basal striations in the epithelial cells of the striated ducts?

Now for the esophagus.