The glycoconjugates of the human fundic mucosa were characterized at the ultrastructural level by means of direct (Helix pomatia agglutinin-gold complex) and indirect lectin techniques (Concanavalin A and horseradish peroxidase-gold complex; wheat germ agglutinin and ovomucoid-gold complex). Surface mucous cells and mucous neck cells secreted O-glycoproteins with N-acetylgalactosamine and N-acetylglucosamine residues at the non reducing terminus of the saccharidic chain. The secretory granules of the mucous neck cells showed condensed areas slightly reactive to ConA. The results obtained in the chief cells suggest that these cells secrete N-glycoproteins rich in mannose and/or glucose residues. "Transitional cells", presenting both morphological characteristics and lectin binding pattern intermediate to the mucous neck and chief cells have been observed. The surface of the intracellular canaliculi of the parietal cell was labelled by HPA, WGA and ConA. In the neck region of the gastric glands, immature parietal cells containing abundant mucous granules reactive to HPA, WGA and ConA were observed. The present results further corroborate the existence of a common cell precursor for surface mucous, mucous neck and parietal cells. In a further step, mucous neck cells gradually differentiate into chief cells the transitional cells being an intermediate stage.
Gallbladder mucus is mainly composed of glycoproteins, which seem to play a critical role in cholesterol nucleation during gallstone formation. The biosynthetic pathway and sequential processing as well as the characterization of the oligosaccharide side-chains of human gallbladder secretory glycoproteins have not been completely defined. The aim of the present study is the subcellular characterization of the glycoproteins in the principal cells of human gallbladder. Principal cells of normal human gallbladder were studied by means of a variety of cytochemical techniques, including lectin histochemistry, enzyme and chemical treatments, immunocytochemistry and lectin-gold technology. Fucose, galactose, N-acetylglucosamine, N-acetylgalactosamine and N-acetylneuraminic acid residues were detected in mucous granules, Golgi apparatus and apical membrane of principal cells. Mannose residues were only observed in dense bodies. Oligosaccharide side-chains of the glycoproteins contained in the biliary mucus are synthesized in the Golgi apparatus of the principal cells of the gallbladder epithelium and are also contained in the mucous granules of these cells. Terminal N-acetylneuraminic acid(alpha 2-3)galactose(beta 1-3)N-acetylgalactosamine, N-acetylneuraminic acid(alpha 2-3)galactose(beta 1-4)N-acetylglucosamine and galactose(beta 1-4)N-acetylglucosamine sequences are contained in the oligosaccharide chains of gallbladder mucus glycoproteins. The dense bodies detected in the cytoplasm of the principal cells contained N-linked glycoproteins. Mucin-type O-linked glycoproteins were the main components of the mucous granules although some N-linked chains were also detected.
P aneth cells , originally described by Schwalbe (1872) and later by Paneth (1888), are normally located at the base of the crypts of Lieberkühn in the small intestine of many mammals, except carnivores. They are easily recognized by a large number of eosinophilic granules located in the supranuclear portion of the cell. Electron microscopic studies (Satoh et al. 1990;Staley and Trier 1965;Hally 1958) have revealed the structural complexity of Paneth granules. These granules are characterized in several species, including rat and human, by an electron-lucent peripheral halo of variable thickness surrounding a large electron-dense core (Satoh et al. 1990).The functions of the Paneth cells have not been clearly established. However, it has been demonstrated that Paneth cells produce and secrete antibacterial agents (lysozyme, cryptidin, and immunoglobulin A), hydrolases, lipases, and growth factors and modulators (Desai et al. 1991;Quellette and Lualdi 1990;Saito et al. 1988;Lechene de la Porte et al. 1986;Poulsen et al. 1986;Senegas-Balas et al. 1984;Erlandsen et al. 1974 Erlandsen et al. , 1976Erlandsen and Parsons, 1973). The granules also contain a zinc-binding protein (Sawada et al. 1994). It has been suggested that goblet and Paneth cells share a common pathway of development (Kedinger et al. 1988;Lopez-Lewellyn and Erlandsen 1980;Lopez-Lewellyn 1979).Lectins are proteins or glycoproteins that bind specifically to carbohydrate groups (Goldstein and Hayes, 1978). They have been widely used in combination with enzymes for in situ characterization of the
In this work, American Iron and Steel Institute (AISI) O1 steel was pack borided in the temperature range of 1123-1273 K for treatment times between 2 and 8 hours. A kinetic model was proposed for estimating the boron diffusion coefficients through the Fe 2 B layers. As a result, the boron activation energy for the AISI O1 steel was estimated as 197?2 kJ mol 21 . This value of energy was compared to the literature data. In addtion, to extend the validity of the present model, two additional boriding conditions were done. The Fe 2 B layers grown on AISI O1 steel were characterised by use of the following experimental techniques: scanning electron microscopy, X-ray diffraction analysis and Daimler-Benz Rockwell-C indentation technique. Finally, the scratch and pin on disc tests for wear resistance were respectively performed using an LG Motion Ltd and a CSM tribometer under dry sliding conditions.
The ultrastructure of the renal corpuscle and tubule of Sparus auratus is described. The parietal epithelium in Bowman's capsule is flattened with occasional cilia; podocytes are large with bundles of perinuclear microfilaments, a large vacuole and occasional cilia; a filtration slit membrane can sometimes be identified; mesangial cells are placed peripherally and among the walls of the capillaries. The neck segment is short and ciliated; it lacks the mucous cells which appear in some teleosts. The first proximal segment has columnar cells with a well developed brush border, and some cilia, large light vacuoles and many lysosomes appear in the apical zone; the second proximal segment has taller cells than the former, which appear with a less dense brush border, containing numerous multivesicular bodies; the third proximal segment, which has cells similar to the previous ones, possesses a less developed brush border and numerous mitochondria scattered all over the cytoplasm. No distal tubule is present. There is a collecting tubule with columnar cells with few microvilli and some apical mucin granules which empty into the collecting duct.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.