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.     

Histochemistry of glycoconjugates in the goat nasolabial skin with special reference to eccrine glands

The histochemistry of glycoconjugates in the nasolabial skin of the goat has been studied by means of a series of selected methods of light microscopy. The epidermis of the nasolabial skin was found to contain neutral and acid glycoconjugates with different saccharide residues. The secretory epithelial cells and secretory substances of the sebaceous glands contained primarily neutral glycoconjugates, whereas those of the apocrine glands involved largely strongly acidic and neutral glycoconjugates. In the epithelial cells and secretory substances of the nasolabial eccrine glands, glycoconjugates involved were characteristically strongly neutral but weakly acidic in nature. From the present results, the histophysiological significance of glycoconjugates in the particular histologic structures of the nasolabial skin has been discussed with special reference to the functions of this particular skin type in the goat.     

Histological features and histochemistry of the mucous glands in ventral skin of the frog (Rana fuscigula)

The glycoconjugate components of secretory granules were analyzed in cells of mucous glands in ventral skin from Rana fuscigula. The analysis was done with standard histochemical methods on semithin glycol methacrylate-embedded tissues. The staining patterns in semithin sections were comparable to those using paraffin-embedded tissue while the cytological detail was better preserved. The mucous glands contained at least two different types of secretory cells lining the lower two-thirds of the mature gland: a principal cell type filled with dense staining secretory granules and a solitary type containing paler staining, globular secretory granules. The principal type of cell contained variable amounts of acid glycoconjugates; predominantly carboxylated but also variably carboxylated and weakly sulfated glycoproteins. Other secretory cells contained mainly neutral glycoproteins. The results indicated that the mucus is a heterogeneous substance and that one cell type may produce different secretory products. We suggested that the variability in histochemical staining might be related to the sequence of biosynthesis of the secretory granule.     

Histochemistry of glycoconjugates in the nasolabial skin of the Japanese serow (Capricornis crispus, Artiodactyla, Mammalia) with special reference to glandular structures

The histochemistry of glycoconjugates in the nasolabial skin of the Japanese serow ( Capricornis crispus ) was studied by light microscopic histochemical methods, particularly lectin histochemistry. The eccrine glands present exhibited neutral and acidic glycoconjugates with different saccharide residues (alpha-L-fucose, beta-D-galactose, beta-N-acetyl-D-glucosamine, alpha-D-galactose and N-acetyl-neuraminic acid) especially in the cells of the secretory acini, the free surface of the collecting duct cells also showed distinct positive reactions with most of the histochemical methods. The thick epidermis of the nasolabial skin contained smaller amounts of glycoproteins. The results obtained are discussed with regard to possible functions of the glandular secretions. This substance mixture may particularly improve water retention on the skin surface, and protect against physical damage as well as microbial contamination. There seem to be no basic differences of muzzle functions between wild and domesticated bovine species.     

Further aspects of the general antimicrobial properties of pinniped skin secretions

In 2 pinniped species with varying hair densities (the northern fur seal Callorhinus ursinus, and the common seal Phoca vitulina), the enzyme lysozyme and the peptide group beta-defensins are demonstrated for the first time as products of the apocrine glands and the sebaceous glands in the common integument of mammals. These antimicrobial substances are also found in the epithelial lining of the hair follicles, between the corneal lamellae of the epidermis, and in dermal histiocytes. Thus, it becomes obvious that another general defense mechanism against microbes, in addition to free sugars (Meyer et al. [2000] Aspects of general properties of skin secretions in the common seal Phoca vitulina. Dis Aquat Org 41:77-79), is active on the skin surface of haired marine mammals to which glandular lysozyme and defensins are regularly transported, so that this biotope is protected against the proliferation of potential pathogens, e.g. bacteria and fungi.     

Histochemistry of glycoconjugates in the skin of the bovine muzzle, with special reference to glandular structures

The distribution of glycoconjugates in the muzzle of young adult Holstein cows has been studied by means of selected light-microscopic histochemical methods, including lectin histochemistry. In the skin layers, strong reactions were confined to intercellular substances in between the cells of the vital epidermis, exhibiting neutral glycoconjugates mainly with alpha-D-galactosyl and N-acetyl-D-galactosaminyl residues. In the nasolabial glands, distinctly positive staining for neutral glycoproteins with various saccharide residues (alpha-D-galactose, alpha-N-acetylgalactosamine, D-galactose-beta(1----3)D-N-acetylgalactosamine, beta-D-galactose), and for smaller amounts of acidic glycoconjugates, was found in the secretory cells and the luminal secretion. The cells of the excretory duct system showed weak to moderate reactions (alpha-D-galactose, beta-D-galactose), only the collecting ducts reacted positively for acidic glycoproteins with sialyl residues. The results obtained are discussed in view of muzzle function, with special reference to the salivary nature of the secretion of bovine nasolabial glands.     

Histochemical investigations on the secretory cells in the oesophagogastric tract of the Eurasian green toad,Bufo viridis

The secretory cells of the oesophagogastric tract of the Eurasian toad, Bufo viridis, were examined using standard histochemical methods and lectin histochemistry. Two goblet cell types were found in the oesophageal epithelium, differing in their morphology and the histochemical features of the secretory granules. These contained mainly acidic glycoconjugates, both sulphated and carboxylated, and a small amount of pepsinogen. Type I goblet cells contained stable class-III mucosubstances, which were absent in Type II. No pluricellular oesophageal glands were found. The oesophagogastric junction had a superficial epithelium similar to that of the oesophageal epithelium, with alveolar pluricellular glands, secreting stable class-III mucins, and few oxynticopeptic cells. The gastric mucosa presented secretory cells both in the surface epithelium and in the gastric glands. Superficial and foveolar cells produced neutral mucins with Gal1,3GalNAc residues. Neck cells, oxynticopeptic cells and endocrine cells were found in the gastric glands. Neck cells produced stable class-III mucosubstances. A functional gradient was observed in the oxynticopeptic cells from the oral to the aboral fundus, with a decrease in pepsinogen secretion towards the aboral fundus and a possible increase in HCl secretion. In the pyloric mucosa, the oxynticopeptic cells disappeared and the glands produced only neutral mucins, without stable class-III mucosubstances.     

Histochemistry of glycoconjugates in the secretory epithelium of the goat bulbourethral gland

To investigate the histochemical nature of the secretory epithelium lining the goat bulbourethral gland, glycoconjugates contained in these secretory epithelial cells have been studied by means of light- and electron-microscopic histochemistry. The methods employed involved a series of conventional staining and peroxidase-labeled lectin diaminobenzidine procedures together with combined selective methods such as digestion with enzymes. According to the results obtained in the present work, the secretory cells of the goat bulbourethral gland can be grouped into two types: cells with glycoconjugate-rich granules and those with less amounts of glycoconjugates. The gland is at least dual in the nature of its secretory activities.     

Light microscopic detection of sugar residues in glycoconjugates of salivary glands and the pancreas with lectin-horseradish peroxidase conjugates. II. Rat

Summary Salivary glands and pancreases from male rats were stained with a battery of ten different lectin-horseradish peroxidase conjugates. Qualitative and quantitative differences were observed in the content of terminal sugar residues in stored secretory glycoproteins in parenchymal cells of glands having a similar histological structure. Heterogeneity in the content of secretory glycoconjugates was also found between cells in the same exocrine glands, which were previously thought to be identical on the basis of classical morphological and histochemical staining studies. Similar differences were observed in the structure of glycoconjugates associated with the apical surface of epithelial cells lining glandular excretory ducts. Intercalated ducts presented a gland specific staining pattern different from that of the glandular secretory cell population, whereas striated duct and interlobular duct epithelial cells stained similarly in all major rat exocrine glands. A comparison of lectin binding patterns in identical histological sites in the mouse, reported in a companion paper, is provided, and the similarities and differences between these two rodent species are discussed. In addition to providing valuable information concerning the localization and structure of tissue complex carbohydrates, a comparison of staining in the same tissue sites with labelled lectins reported biochemically to have similar binding specificity has revealed interesting differences in the binding specificity of these macromolecules.     

Enzyme histochemical studies of the general body surface apocrine glands in the domestic cat]

With enzyme histochemical methods, the distribution and the activities of various oxidative and hydrolytic enzymes in the apocrine glands of the general body surface of the domestic cat were investigated. The results obtained support the view that these glands are clearly active in function. On the whole, however, the relatively weak enzyme activities in the secretory portion of the glands point to only unimportant secretion production rates.     

Lectin histochemical study on the infraorbital gland of the Japanese serow (Capricornis crispus)

Histology and lectin histochemistry were performed in the infraorbital gland of the Japanese serow. The gland is composed of glandular tissues and a pouch filled with the secretion. The tissues consist of an inner layer of sebaceous glands and an outer layer of apocrine glands. The male sebaceous layer is made up of the ordinary type, whereas the female's layer consists of the ordinary and modified types. In the apocrine gland stained with Arachis hypogaea (PNA), nine different patterns of glandular tubules were distinguished on the basis of staining of the cytoplasm, the Golgi area of secretory cells and secretion. Secretory modes of apocrine secretion and exocytosis were included in these stainings. Myoepithelial cells stained constantly with Glycine max (SBA) except when only the Golgi area of secretory cells was positive. The modified sebaceous gland was stained with PNA, SBA, Ricinus communis I (RCA), Triticum vulgaris (WGA), Canavalia ensiformis (Con A) and Ulex europaeus I (UEA), while the ordinary type was positive in PNA, RCA, SBA, WGA and Con A. The secretion in the pouch was stained with PNA, RCA, SBA, Dolichos biflorus (DBA), WGA and Con A. These findings suggest that the modified sebaceous gland contains large amounts of glycoconjugates and the apocrine gland shows a cyclic secretory process of apocrine secretion and exocytosis.     

Morphology and glycoconjugate histochemistry of the palpebral glands of the adult newt, Notophthalmus viridescens.

The eyelids of the newt were studied in 10 microns serial paraffin and 1-2 microns plastic sections using standard histological stains and special stains for glycoconjugates. The eyelids contain four different glands. Simple acinar serous and simple acinar mucous glands occur in the skin; unicellular mucous glands occur in the conjunctiva; and convoluted tubular seromucous glands are present in connective tissue beneath the conjunctiva. The first two are identical to cutaneous glands found elsewhere on the head and body. The simple acinar serous glands are surrounded by myoepithelial cells and release their secretion, which is composed largely of proteins with minimal glycoconjugate content, by a holocrine mechanism. The secretory product of the simple acinar mucous glands is composed of neutral glycoconjugates with a minor content of acidic glycoconjugates; the mucin exhibits strong PAS and PAPD staining and weak staining by AB and PAPS methods. The unicellular conjunctival mucous glands secrete both neutral and acidic glycoconjugates as shown by positive reactions with PAS, PAPD, PAPS, and AB methods. Convoluted tubular seromucous glands in the ventral eyelid synthesize both proteins and neutral glycoconjugates. The mucous secretions of the conjunctival glands probably provide lubrication and protection for the cornea.     

Distinct expression of calnexin in major human salivary glands

Calnexin (Cnx) has been characterized as a membrane-bound protein that transiently interacts in a unique chaperone system with newly synthesized glycoproteins in order to allow the establishment of their proper tertiary and, in most cases, quarternary structures. The aim of the study was to identify and to locate the expression of Cnx in the three major salivary glands of humans by different methods. Strong expression of Cnx protein and mRNA were generally found in serous salivary secretory units. With regard to mucous secretory units, expression of Cnx was only detectable at a low level in mucous acinar cells of sublingual glands, but not of submandibular glands. Expression of Cnx was always preserved in the surface epithelium of intralobar and interlobular duct segments. In addition, expression of Cnx was detected in sebaceous glands of parotid tissues, with a distribution pattern resembling that seen in sebaceous glands of the normal skin. In conclusion, production of saliva is associated with the expression of Cnx. Synthesis of molecules in mucous secretory units is not necessarily associated with a strong Cnx expression, whereas synthesis in serous secretory units apparently is. The tissue-specific Cnx expression is also paralleled by the observation that the secretions produced by the major salivary glands differ in their composition and amount.     

The preputial gland of the Japanese serow Capricornis crispus: ultrastructure and lectin histochemistry

Preputial glands of the Japanese serow were found to consist of the modified sebaceous gland and apocrine gland in both sexes. In the modified sebaceous gland, cells transformed gradually toward the lumen from plentiful cytoplasm to a sponge-like network. Lipid droplets were observed in mitochondria of differentiating cells. By lectin histochemistry, differentiating cells were stained with Arachis hypogaea (PNA), Triticum vulgaris (WGA) and Canavalia ensiformis (Con A) lectins, while secretory cells of the apocrine gland revealed various stainings with PNA, Glycine max, Dolichos biflorus, WGA and Con A lectins. These findings suggest that glycoconjugates may have an active function in the preputial gland.     

Glands of the eyelids of rhesus monkeys (Macaca mulatta)

The various glands of rhesus monkey eyelids and human eyelids are similar. Numerous modified sebaceous glands are located along the tarsus. These conform with the meibomian glands, while typical sebaceous glands associated with the hair follicles of the lashes are consistent with the glands of Zeis. Lobules of accessory lacrimal tissue, corresponding to the glands of Krause and Wolfring, are located in the conjunctiva of the fornix and along the orbital border of the tarsal plate. Goblet cells are plentiful in the mucosa of the palpebral and bulbar conjunctiva, and along the lid margin are the sweat glands of Moll.     

Ultrastructural localization of acidic glycoconjugates with the low iron diamine method

The present study has applied the low iron diamine (LID) method at the ultrastructural level to demonstrate acid glycoconjugates. We have examined rat epiphyseal cartilage, human bone marrow, rat tracheal glands, and mouse sublingual glands stained with LID prior to embedment. The LID staining appeared to require postosmication for adequate visualization at the electron microscope level. Thiocarbohydrazide-silver proteinate (TCH-SP) staining of thin sections variably enhanced LID reactive sites. LID-TCH-SP stained carboxyl and sulfate groups of glycosaminoglycans in the extracellular cartilage matrix, secretory granules, and expanded Golgi saccules of chondrocytes. In human bone marrow, LID-TCH-SP variably stained the cytoplasmic granules, known to contain sulfated glycosaminoglycans, and the external surface of the plasma membrane of leukocytes. Moderately strong LID staining was observed in secretory granules in mucous tubules of rat tracheal glands, known to contain sulfated glycoproteins, and in acinar cells of mouse sublingual glands, known to contain a sialoglycoprotein. The lack of sulfated glycoconjugates in acinar cells of the mouse sublingual gland was confirmed by their failure to stain with the high iron diamine method. Thus these studies indicate that the LID and LID-TCH-SP methods are useful for the ultrastructural localization of carboxylated and sulfated glycoconjugates in extracellular and intracellular sites.     

The cytochemistry of glycoconjugates in the planum nasolabial gland of the goat as studied by electron microscopic methods

Summary In the planum nasolabial glands of the goat, glycoconjugates of glandular and duct cells have been studied by means of a series of electron microscopic cytochemical methods. In the glandular cells glycoconjugates with vicinal diol groupings were present in secretory granules, certain elements of the Golgi complex, lysosome-like dense bodies, the surface coat of the plasma membrane, the majority of intracellular cytomembranes, glycogen particles and the basal lamina. In duct cells, glycoconjugates with the same properties were localized in similar ultrastructures, except for secretory granules, which were not detected in these cells. By lectin cytochemistry, glycoconjugates in glandular cell secretory granules contained a variety of saccharide residues such as -d-mannose, -d-glucose,N-acetyl-d-glucosamine and -l-fucose. The cytochemical properties of the secretory glycoconjugates are discussed in relation to the physiological functions performed by the planum nasolabial glands in the goat.     

Secretory glycoconjugates in the epithelium of the goat prostate

Summary Secretory glycoconjugates in the epithelium of the goat prostate were investigated with various electron microscopical histochemical methods that involved periodic acid—thiocarbohydrazide—silver proteinate, colloidal gold-labelled lectin and related procedures. The three types of cells in the epithelium previously differentiated with the light microscope were substantiated: mucus-producing cells, protein-secreting cells and cells intermediate between both types. These three cell types contained varying amounts of neutral glycoconjugates; the histochemical nature of these carbohydrates was determined with particular emphasis upon the histophysiological functions of the accessory sex glands.     

Detection of Hepatoid Glands and Distinctive Features of the Hepatoid Acinus

In the 1920s–1930s, skin glands of a new type, hepatoid glands, were described in 13 mammal species (Rodentia, Canidae, and Bovidae). The hepatoid glands resemble sebaceous glands in their morphology, bur radically differ from them in specific structure of the acinus and another type of secretion. Later, these data either could not be confirmed or were considered insignificant and the hepatoid glands were described as modified sebaceous glands, glands with uncertain function, or modifications of epidermis. Based on the studies of various hepatoid glands in 22 species of Carniviora and Artiodactyla, the authors described in detail the characteristic features of the hepatoid acinus, which allow a precise discrimination of hepatoid and sebaceous glands. Extracellular secretory canaliculi have been described in the hepatoid glands, as well as the richness of hepatoid glands in protein, distribution of hydrophobic lipids in certain hepatoid glands, and formation of excretory ducts and cysts. The hepatoid glands are a source of great amounts of protein secreted in the merocrine way; the secretory substance of some of these glands has a strong odor.     

Cellular dynamics of the outer layers of the hair follicle of fine-wool sheep during the phase of stable hair growth

The structure, origin, and migration of outer sheath cells of the hair follicles of domestic sheep were studied by electron microscopic, autoradiographic, and histochemical (glycogen) methods in order to understand the role of this layer in hair morphogenesis. We demonstrated that the cells of the outer layers of the outer sheath interpose into the inner “companion” layer of the outer sheath. Although this process takes place all along the hair follicle from the lower bulb up to the sebaceous glands orifices, it mainly takes place over the bulb. Labeled cells interposed into the companion layer reach sebaceous glands orifices more than 24 h faster than labeled cells of the inner sheath and hair, because these cells included the label not in the bulb cambium (as hair and inner sheath) but over the bulb, and from this point they start movement. Interposition of cells into the companion layer must cause increase of its volume and additional volume supposed to be led away into the pillar canal around the hair near the sebaceous glands orifices. This can provide the mechanism of the hair and inner sheath promotion to sebaceous gland orifices.