The chicken anterior lingual glands: structural study of carbohydrate chains by lectins and glycosidases

Histochemical and ultrastructural study of the chicken salivary palatine glands

Salivary glands are a good model to investigate the relationship between cell secretion and glandular structure. Most studies of this organ deal with mammals, but we are interested in a morphofunctional characterization of these glands in poultry in relation with particular feeding habits. For this purpose, conventional and lectin histochemical methods as well as ultrastructural methods have been applied to the chicken lateral and medial palatine salivary glands. It was found that periodic acid-Schiff (PAS)-positive, alcianophilic, and metachromatic or orthochromatic cells were present with a more homogeneous distribution pattern in lateral glands than in medial palatine glands. Lectin staining depended on the lectin type that was applied, but also on the glandular part both in lateral and medial glands. Ultrastructural studies showed cytoplasmic membranous structures with a scattered granular or filamentous content depending on the secretory cell. In conclusion, morphofunctional characteristics of salivary glands of chicken suggest that their products are involved in lubrication and humidification of food ingested, and probably in protection of the oral surface, as has been previously described for other animals showing similar histochemical staining patterns.

Histological and histochemical studies on the lingual, preglottal and laryngeal salivary glands of the Japanese quail (Coturnix coturnix japonica) at the post-hatching period

The postnatal development and histochemistry of mucins of the lingual, preglottal and laryngeal glands in the quails were investigated by means of light microscopy using specific staining for complex carbohydrates. In this study, the tongues were taken from female and male quails from day 1 to day 60 after hatching. The salivary glands in quail's tongue comprised the lingual gland, with lateral and medial (paraentoglossal gland) portions that differ in morphology and histochemical staining, and the preglottal gland, with two lateral portions and one medial portion. The medial portion of the preglottal gland, which extended to the row of the laryngeal papillae on each side of the glottis, was described as the laryngeal gland. The salivary glands were present at hatching and their cells were functionally mature and secreted mucins. In quail of all ages, the histochemical reactions revealed that the cytoplasms of the secretory cells of the preglottal, laryngeal and paraentoglossal gland (medial portion of lingual gland) contained sialomucins and weakly sulphated epithelial mucins. Neutral mucins were absent in the paraentoglossal gland, while a small amount of neutral mucins was present in other glands. The mucins with vicinal diol groups, sialomucins and weakly sulphated epithelial mucins were mixed within the secretory cells of all the glands. All the histochemical reactions were restricted to the supranuclear regions of the secretory cells within the lateral portion of the lingual gland. In conclusion, the contents of mucins in the lingual, preglottal and laryngeal glands varied between different age groups, however, no differences in the glands' histochemistry between male and female quails were observed.

Histochemical study of magellanic penguin (Spheniscus magellanicus) minor salivary glands during postnatal growth

The histological and histochemical features of the minor salivary glands during postnatal development have been generally associated with the type of food ingested. However, recent studies support the fact that these salivary glands develop independently of the diet; in fact, minor salivary glands have similar morphological and histochemical characteristics in adult individuals of species with different diet regimens. Thus, the aim of this study was to characterize the developmental morphology of the penguin minor salivary glands and to contrast them with minor salivary glands of other species. The tongue, palatine, and mouth cavity (bottom) minor salivary glands of newborn, 1- to 20-day-old, and adult magellanic penguins were studied with hematoxylin-eosin, periodic acid-Schiff, alcian blue, toluidine blue, and lectin histochemistry. Minor salivary glands were present at all ages, although they were only moderately developed in animals less than 15 days old. After this age, glands were abundant in all age groups; in addition, cells from the glandular epithelium were functionally mature and secreted mucins. Nevertheless, in newborn to 15-day-old penguins, mucins were located only at the apical cytoplasm of mucous cells. In all ages, mucous cells displayed periodic acid-Schiff-positive, alcianophilic, and metachromatic reactions; among mucous cells, other orthochromatic cells appeared interspersed. From 15 days on, histochemical reactions became more intense until adulthood, and the cytoplasm of secretory cells was filled with glycoproteins and sulfomucins. Moreover, lectins bound to different oligosaccharides in mucous cells, depending on the stage of maturation of the glands. In conclusion, penguin minor salivary glands are already present at birth, and show progressive and quantitative increases in mucous secretion during postnatal development. These changes are necessary not only for nutrient ingestion, but also for nonimmune protection of the buccal cavity.

Sialic acids in the chicken anterior lingual glands detected by lectins combined with enzymatic degradation and oxidizing agents

The chicken anterior lingual glands contain a large amount of sialoglycoconjugates. This study is aimed at discriminating between them, on the basis of the degree of acetylation and the acceptor sugars, by means of lectins combined with neuraminidase digestion and treatment with oxidizing and deacetylating agents. In the anteromedial part of lingual glands, only low concentrations of periodate-labile sialic acid having alpha 2-3,6-galactose and alpha 2-6-N-acetylgalactosamine acceptor sugars were present. Mostly, C7 and/or C8 acetylated sialic acids occurred, while C9 acetylated sialic acid linked alpha 2-3-galactose and alpha 2-6-N-acetylgalactosamine were restricted to some cells. In the anterolateral part, sialic acid linked alpha 2-6-N-acetylgalactosamine was not acetylated, while sialoderivatives alpha 2-3 linked to galactose were mainly C9 acetylated.

Basic and lectin histochemistry for studying glycoconjugates in the lingual salivary glands of the Japanese quail (Coturnix coturnix japonica)

Traditional non-lectin staining methods and lectin histochemistry combined with specific exoglycosidase digestion were used to investigate the histological structure of these glands and to visualize the occurrence and composition of salivary glycoconjugates. The quail lingual glands comprise the anterior lingual gland, with rostral and caudal portions that differ in morphology and histochemical staining, and the posterior lingual gland devoid of regional differences. Carbohydrate histochemistry further differentiated the secretory structures by revealing a heterogeneous cell population of tubules within the rostral and caudal portions of the anterior gland, and a rather homogeneous staining of the tubuloalveolar elements in the rostral portion of the anterior lingual gland and in the posterior gland. Tubuloalveolar secretory cells mainly produced sulphate-containing molecules. In addition, sialoglycoconjugates were present in both anterior and posterior lingual glands, whereas fucoglycoconjugates were visualized only in the anterior gland.