Carbohydrate histochemistry of the opossum submandibular and major sublingual glands

Microscopy of the echidna sublingual glands

The secretory units and duct system of the echidna sublingual glands exhibit subtle architectural modifications to accommodate the viscous secretion produced by these glands. The glands are compound tubular glands, the secretory units of which are elongate with open lumina and consist only of mucous cells. Closely packed spindle-shaped myoepithelial cells invest the secretory units, but are absent around the ducts. The branched secretory tubules open into an abbreviated duct system characterized by wide lumina. Striated ducts normally associated with the second portion of the intralobular duct system are absent. The duct system shows the most obvious modification of general salivary gland architecture presumably to accommodate the viscous secretion propelled from the secretory units by surrounding myoepithelial cells.

Developmental changes of sugar residues and secretory protein in mucous cells of the early postnatal rat parotid gland

Mucous cells have been identified in the terminal portions of the early postnatal parotid gland in human and rat, although mature parotid gland acini are composed of serous cells or seromucous cells. Previously, Ikeda et al. demonstrated that mucous cells are present in the rat parotid gland on days 1 to 8 after birth and that the secretory granules within these mucous cells share some histochemical characteristics with mature serous cells. However, it is still not clear whether the mucous cells change into serous cells as the gland develops. The purpose of this study was to determine whether the mucous cells that appear in the early postnatal rat parotid gland change into serous cells. Parotid glands were obtained from male or female Wistar rats (aged 0-14 days and adults). Fixed tissue sections were reacted with soybean agglutinin (SBA) and wheat germ agglutinin (WGA) to detect glycoconjugates, or were stained using an anti-neonatal submandibular gland protein B1 (SMG-B1) antibody to identify serous acinar cells. The sections were observed by transmission electron microscopy. Electron microscopy revealed that cells with characteristics intermediate between those of mucous and serous cells (transitional cells) appeared around day 8 and that the nuclei of these cells did not show chromatin condensation, a characteristic of apoptotic cells. Lectin histochemistry showed that the mucous cells had the same sugar residues as the serous cells, which appeared after day 10. Immunohistochemistry with an anti-SMG-B1 antibody gave a positive reaction not only in the cells with highly electron-dense granules but also in the electron-dense cores of bipartite or tripartite granules in the transitional cells. Cells with morphological characteristics intermediate between those of mucous and serous cells (transitional cells) appearing in the early postnatal rat parotid gland begin to produce B1-immunoreactive protein common to serous acinar cells during development of the gland.

Histological and histochemical studies on the chicken lingual glands

1. Morphological and histochemical observations were done on the chicken anterior and posterior lingual glands. Histology, ultrastructure and glycoconjugate histochemistry were investigated by means of light and electron microscopy using staining specific for complex carbohydrates. 2. In the anterior lingual glands there are lateral and medial zones showing different morphological and tinctorial features. The secretory cells are typical mucous cells. 3. Histochemical reactions revealed the presence of acidic glycoconjugates with terminal sialic acid residues, and glycoconjugates vicinal diol and sulphate groupings in the secretory granules. 4. It is suggested that the main functions of lingual glands are the lubrication of boli and protection from micro-organisms.

Characterization of the muscarinic cholinergic receptor in the opossum (Didelphis virginiana, Kerr) submandibular gland: differences in receptor density and subtype compared with higher mammalian species

1. Kinetic, saturation and inhibition radioligand binding experiments with [3H]-N-methylscopolamine and [3H]quinuclidinyl benzilate were used to characterize the muscarinic cholinergic receptor in opossum (Didelphis virginiana, Kerr) submandibular salivary gland membranes. 2. The receptor density in opossum submandibular gland was found to be more than 3-fold higher than in rat, and 22-fold higher than in human, submandibular glands. 3. Inhibitor equilibrium dissociation constants for the antagonists pirenzepine, dicyclomine, atropine, N-methylscopolamine and AF-DX 116 revealed that the muscarinic receptor present in opossum submandibular gland appears to be the M1 subtype rather than the M3 subtype found in human and rat.

Glycoconjugates in the secretory epithelium of the chicken mandibular gland

In the secretory epithelium of the chicken mandibular gland, glycoconjugates have been studied by means of histochemical methods of light and electron microscopy. In light microscopy, a series of histochemical procedures have been employed which included lectin--peroxidase--diaminobenzidine methods and a digestion technique with neuraminidase or alpha-amylase. In electron microscopy, a battery of methods were used that corresponded to those employed in light microscopy. In the secretory cells of the chicken mandibular gland, vicinal diol- and sulphate-containing glycoconjugates with sialic acid, alpha-D-mannose, alpha-D-glucose and beta-D-galactose residues were visualized and the possible histophysiological significances of such glycoconjugates were discussed with special reference to the functions of the salivary gland.

Morphology and histochemistry of the mandibular gland of the Australian brush-tail possum Trichosurus vulpecula (Marsupialia)

A histological, ultrastructural and histochemical study of the mandibular gland of the Australian possum Trichosurus vulpecula revealed essentially similar features as those described earlier for the mandibular gland of the taxonomically relatively unrelated American opossum Didelphis. The secretory endpieces consist of a branched tubular part, composed of serous cells whose secretion granules contain neutral glycoproteins, and terminal acini, consisting of seromucous cells containing small amounts of sialomucins. Relatively short intercalated ducts lead to striated ducts of variable ultrastructural appearance. The striated ducts run in bundles in the center of each sublobule of the gland. The possible functional significance of the abundance and variability in ultrastructure of the striated ducts is discussed.