Cytochemistry of sialoglycoconjugates, lysozyme, and ß-defensin in eccrine glands of porcine snout skin as studied by electron microscopy.

In most mammals except for humanoid primates, eccrine glands are confined to the skin of a series of specific body regions. Sialic acids and antimicrobial substances exhibit various functional properties and serve as a component of nonspecific defense against micro-organisms, respectively. In this study, the distribution of these moieties was studied by electron microscopic histochemical methods. The eccrine glandular acini consisted of two types of dark cells as well as clear cells. The secretory granules and Golgi apparatus of both types of dark cells contained sialic acid residues linked to α2-6Gal/GalNAc. On the other hand, sialoglycoconjugates with Siα2-3Galß1-4GlcNAc sequence were confined to those of the Type II dark cells. In addition, lysozyme and ß-defensin were mainly detected in the secretory granules of the Type II dark cells. These secretory products may create a defensive barrier against microbial invasion and play an essential role in preservation of the integrity of porcine snout skin as a sensory organ.

Histochemical distribution of sialic acids and antimicrobial substances in porcine carpal glands.

The localization of sialic acids and antimicrobial products (lysozyme, IgA, lactoferrin, ß-defensin 2) as well as Rab3D in the carpal glands of pig was studied by sialoglycoconjugate histochemistry and immunohistochemistry. The secretory epithelium of the carpal glands consisted of dark and clear cells. The dark cells of these glands exhibited high levels of sialoglycoconjugates, including O-acetylated sialic acids, whereas the localization of sialic acids linked to α2-3Gal1-4GlcNAc was confined to a subpopulation of the dark cells. Furthermore, all antimicrobial substances and Rab3D were mainly detectable in a subpopulation of the dark cells. The results obtained are discussed with regard to the functional significance of these glands. Our findings suggested that Rab3D is involved in the secretory regulation of sialoglycoconjugates and antimicrobial substances. These secretory products may create a defensive barrier against microbial invasion and play an essential role in the preservation of skin integrity.

Immunocytochemical localization of lysozyme and beta-defensin in the apocrine glands of the equine scrotum.

The present study revealed in detail the subcellular localization of lysozyme and beta-defensin in the apocrine glands of the equine scrotal skin, a specific body region. The apocrine glandular cells were equipped with a varying number of secretory granules, a well-developed Golgi apparatus and abundant cisternae of the rough endoplasmic reticulum within their cytoplasm. In these cells, reactive gold particles representing lysozyme were detectable in the secretory granules as well as the Golgi apparatus and elements of the rough endoplasmic reticulum. Additionally, the antimicrobial peptide group of beta-defensin was also localized in the above-mentioned ultrastructures of the secretory cells. The presence and secretion of such substances that may serve as a non-specific defense against microorganisms are suggestive of the protective effect of the secretory production elaborated by the apocrine glands.

Cytochemical characterization of glycoconjugates in the apocrine glands of the equine scrotal skin.

Cytochemistry of glycoconjugates in the apocrine glands in the scrotal skin of the horse was studied using cytochemical methods for electron microscopy, particularly lectin cytochemistry. The secretory cells possessed a variable number of secretory vesicles, a well-developed Golgi apparatus, and abundant cisternae of the rough endoplasmic reticulum. Additionally, the basolateral plasma membrane formed numerous interdigitating folds. Glycoconjugates with vicinal diol groupings were present predominantly in the secretory vesicles, the Golgi apparatus, the surface coat of the plasma membrane, and the majority of the intracellular membranes. With lectin cytochemistry, the secretory vesicles of the glandular cells exhibited glycoproteins with different terminal sugars (alpha-D-mannose, beta-D-galactose beta-N-acetyl-D-glucosamine, and sialic acid). Several sugars were distinctly prominent in the surface coat of the plasma membrane of the secretory cells. The cytochemical properties of the complex glycoconjugates found are discussed in relation to the specific functions of the glandular secretions. These glands may have an important role in not only thermoregulation but protection of the scrotal skin, a specific body region.

Histochemical localization of complex carbohydrates in the nasolabial glands of the Japanese deer (Cervus nippon yakushimae).

The localization of complex glycoconjugates in the nasolabial glands of the Japanese deer (C. nippon yakushimae) was studied using various histochemical methods, including lectin histochemistry, viewed using both light and electron microscopy. The secretory epithelium and luminal secretion of the deer nasolabial glands exhibited neutral and acidic glycoconjugates with different saccharide residues (alpha-D-mannose, alpha-N-acetyl-D-galactosamine, beta-D-galactose, beta-N-acetyl-D-glucosamine and sialic acid). Additionally, O-acetylated sialic acids were detectable in the glandular acini. The results obtained are discussed with regard to the specific functions of the glandular secretion, which may particularly improve water retention on the skin surface and protect against physical damage as well as microbial contamination. Furthermore, our results support the view of a salivary nature of this gland type.

Aspects of glycoconjugate production and lysozyme- and defensins-expression of the ceruminous glands of the horse (Equus przewalskii f. dom.).

The distribution of complex glycoconjugates and antimicrobial substances in the ceruminous glands of the horse (Equus przewalskii f. dom., type: pony) was studied using carbohydrate histochemical and immunohistochemical methods. The epithelial cells and luminal secretion of these glands exhibited considerable amounts of glycoconjugates with various saccharide residues, such as alpha-D-mannose, alpha-L-fucose, beta-D-galactose, beta-N-acetyl-D-glucosamine and sialic acid, including O-acetylated sialic acid. Several sugars (alpha-D-mannose, alpha-L-fucose, and beta-D-galactose) were also detectable in the secretion of sebaceous glands present. Additionally, lysozyme and the peptide group of beta-defensins are demonstrated as products of the apocrine ceruminous glands and sebaceous glands. The results obtained are discussed with regard to the functional significance of the glandular secretions. It is suggested that the complex carbohydrates, lysozyme and beta-defensins found in the ceruminous gland secretions are involved in the function of cerumen as a general antimicrobial protective agent in the external auditory canal.