Salivary demilunes stain intensely with haematoxylin & eosin
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True. Histologists often use two or more different stains together to reveal differences in the tissue they are looking at. By using dyes to apply contrast to different parts of the tissue, the overall structure is made much clearer. Haematoxylin and eosin are two stains which are very often used together.
If a tissue or tissue component binds haematoxylin it is stained a very dark red whereas if it reacts with eosin it stains light red. The proteins and glycoproteins in salivary gland secretory granules are stained by haematoxylin whereas cellular cytoplasm is stained by eosin.
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Mucous alveoli can be distinguished from serous acini by their staining reaction with Alcian Blue
True. Alcian Blue is a stain often used by histologists to detect what used to be called mucopolysaccharides and are now called glycosaminoglycans or GAGs for short. However, alcian blue binds to GAGs because they are highly negatively charged polysaccharides and for no other reason. This means that it will also stain the high molecular weight mucins which are produced by mucous alveoli and all minor salivary glands with the exception of the serous glands of von Ebner.
The mucins are stained because they contain a very unusual 9-carbon sugar call N-acetyl neuraminic acid which is also known as sialic acid (good job). Since mucins have lots of oligosaccharide side chains which have sialic acid as the terminal sugar residue, then they have an overall negative charge which means they will stain with alcian blue.
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Two
wrongs don't make a right
Compare this shot with the picture of the H&E stained section above which is of the same tissue. In that picture the mucous alveolus has not been stained by the H&E. You can see quite clearly the presence of unstained material inside cells but how certain could you be that this wasn't fatty tissue?
Well, fat would not stain with alcian blue. This demonstrates nicely how useful different types of stains can be when used together.
The minor salivary glands of the hard palate are of the serous type
False. You may have been told that there are no minor glands on the hard palate. Well, this isn't exactly true. They are not as common as elsewhere but you can find them. This, however, isn't the reason why the answer to the question is "false".
It's "false" because all minor salivary glands except those associated with circumvallate papillae on the tongue (von Ebner's glands) are mucous secreting not serous.
Striated duct cells actively transport water
False. Striated ducts are largely impermeable to water. If ducts were permeable to water then water would follow ions as they were removed by the striated ducts.
This would mean that saliva would then be isotonic with respect to interstitial fluid when, in fact, it is always hypotonic.
Minor salivary glands are found on all oral surfaces except the gingiva and the anterior part of the hard palate
False. Although rare, they can be found on the hard palate although they are absent in the gingiva.
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