Epithelium of lips and associated structures of the Indian major carp,Catla catla

Structural organization of the epithelium of the lips and associated structures of the Indian major carp,Catla catla, is described. The upper lip is thin and is associated on its dorsal side with a membranous fold of skin and the rostral cap. In contrast, the lower lip is thick and very conspicuous. It is associated on its ventral side with a fold of skin between it and the ventral head skin. The lower lip is divided into a non-projectile portion, a projectile portion and an intermediate groove region. The projectile portion remains folded covering a part of the ventral head skin when the mouth is closed. Their role in relation to the formation of the characteristic feeding tube is discussed. The epithelium of the lips and associated structures is stratified in nature and is composed of the epithelial cells, mucous cells, club cells, lymphocytes and the taste buds. The mucous cells are small, few or even absent and do not appear to secrete profusely at the surfaces of the upper and the lower lips. This suggests that the lips inCatla catla, which feeds on micro-organisms, do not need extra lubrication for protection against abrasion during feeding. In the epithelium at the folds of skin, the voluminous mucous cells secrete profusely and provide extra lubrication to their surface. This reduces the resistance to surface drag during stretching and enables the jaws to protrude with increasing efficiency and swiftness. The club cells are developed additionally to complement the mucous cells in the rostral cap and the upper lip epithelium. Their primary function appears protective in some way, which needs further confirmation. The taste buds, though few in the lower lip, are located in a good number in the upper lip on the characteristic epithelial papillae-like projections, and are projected at the surface. These have been associated with the acute gustatory sense of the fish. The taste buds are absent on the folds of skin where they may not be of much significance.     

Junctional structures in digestive epithelia of a cephalopod

Intercellular junctions have been studied in the epithelia of digestive organs of Sepia officinalis (digestive gland, digestive duct appendages and caecum) by conventional staining, lanthanum tracer and freeze-fracturing techniques. In the three organs studied the same junctional complex occurs, consisting of a belt desmosome, a septate junction and gap junctions. The septate junction is of pleated-sheet type and the gap junction has its particles on the P face of the fracture. Circular structures have been found in the digestive gland septate junctions. Neither continuous nor tight junctions have been found. These results show that Cephalopods have junctional structures very close to those of other Molluscs and of Annelids. Some small differences between the septate junctions of the three organs could be related to their different physiology.     

Ultrastructure and histochemistry of the supportive structures associated with the radula of the slug,Limax maximus

The odontophore and connective tissue-filled portion of the radular sac (called the “collostyle”) of the slug, Limax maximus, were examined by light and electron microscopy. While both of these structures grossly resemble vertebrate cartilage, neither is composed of a type of tissue with the microscopic appearance and histochemical properties of cartilage. The roughly U-shaped odontophore possesses a thin capsule composed of connective tissue. The parenchyma of the odontophore consists of modified muscle cells which are organized into irregular groups by incomplete trabeculae composed of conventional muscle cells. The odontophoral cells are variable in size; they contain glycogen-filled “cores” as well as bundles of peripherally located filaments resembling myofilaments; and they are innervated like muscle cells. The nuclei of the cells are located eccentrically in the glycogen-filled portions of the cells and typically contain prominent nucleoli. The nuclei are surrounded by multiple small Golgi complexes and pleomorphic dense bodies resembling lysosomes. The extracellular matrix of the odontophore is very sparse and contains glycogen and fibrillar material but no histochemically demonstrable acidic mucosubstances. The collostyle consists of a gelatinous type of tissue somewhat like vertebrate mucoid connective tissue. The abundant extracellular matrix contains cross banded filaments, a flocculent material disposed in wavy indefinite strands, and small electron-dense particles. The matrix contains histochemically demonstrable neutral and weakly acidic mucosubstances. The cell population of the collostyle includes solitary muscle cells and fibrocytes containing large quantities of glycogen.     

Lectin histochemistry on mucous substances of the taste buds and adjacent epithelia of different vertebrates

Summary In the present study carbohydrate residues in taste buds (TBs) and adjacent epithelial formations of a teleostean fish, a frog and the rabbit were detected by means of lectin histochemistry. Biotinylated lectins fromPisum sativum (PSA),Arachis hypogaea (PNA),Dolichos biflorus (DBA),Triticum vulgaris (WGA and succinylated WGA),Glycine max (SBA) andUlex europaeus (UEA I) have been applied. The lectins were bound to an avidin-biotin-peroxidase-complex (ABC) and visualized by diaminobenzidine/ H₂O₂. Most intensive reactivity was observed at the taste dise cells of the frog with DBA, S-WGA and SBA. PNA did not bind to the TBs of any of the animals tested. As shown in SBA preparations, sialic acid is present in a nonacylated and an acylated form in the mucosa of the frog's tongue. The TBs of the fish possess all the sugars we looked for except for the disaccharided-galactose-(1–3)--d-N-acetyl-galactosamine (Gal/GalNAc) and sialic acid. The TBs of the rabbit contain GalNAc, as detected with DBA, but not with SBA; and fucose (Fuc), mannose (Man) andN-acetyl-glucosamine (GlcNAc). As revealed by preincubation of the tissue sections with neuraminidase in TB cells of the rabbit, sialic acid masks Gal/GalNAc and GalNAc. These lectin-binding characteristics show that in the TBs of some selected representatives which belong to different vertebrate classes exist different mucous substances. These substances possess different binding characteristics to specific sugars, and this is possibly of particular interest to chemoreception phenomena.Dedicated to Professor Dr. T.H. Schiebler on the occasion of his 65th birthday.Parts of this investigation were presented at the 81. Versammlung der Anatomischen Gesellschaft, March 9–14, 1986 at Lübeck (Witt and Reutter 1986), and at the VII th Congress of the Europaen Chemoreception Research Organization, September 22–26, 1986, at Davos (Reutter and Witt 1987).Supported by the Deutsche Forschungsgemeinschaft (Re 225/9-1)     

Lectin histochemistry on mucous substances of the taste buds and adjacent epithelia of different vertebrates

In the present study carbohydrate residues in taste buds (TBs) and adjacent epithelial formations of a teleostean fish, a frog and the rabbit were detected by means of lectin histochemistry. Biotinylated lectins from Pisum sativum (PSA), Arachis hypogaea (PNA), Dolichos biflorus (DBA), Triticum vulgaris (WGA and succinylated WGA), Glycine max (SBA) and Ulex europaeus (UEA I) have been applied. The lectins were bound to an avidin-biotin-peroxidase-complex (ABC) and visualized by diaminobenzidine/H2O2. Most intensive reactivity was observed at the taste disc cells of the frog with DBA, S-WGA and SBA. PNA did not bind to the TBs of any of the animals tested. As shown in SBA preparations, sialic acid is present in a nonacylated and an acylated form in the mucosa of the frog's tongue. The TBs of the fish possess all the sugars we looked for except for the disaccharide D-galactose-(1-3)-beta-D-N-acetyl-galactosamine (Gal/GalNAc) and sialic acid. The TBs of the rabbit contain GalNAc, as detected with DBA, but not with SBA; and fucose (Fuc), mannose (Man) and N-acetyl-glucosamine (GlcNAc). As revealed by preincubation of the tissue sections with neuraminidase in TB cells of the rabbit, sialic acid masks Gal/GalNAc and GalNAc. These lectin-binding characteristics show that in the TBs of some selected representatives which belong to different vertebrate classes exist different mucous substances. These substances possess different binding characteristics to specific sugars, and this is possibly of particular interest to chemoreception phenomena.     

Occurrence of keratinization in the structures associated with lips of a hill stream fish Garra lamta(Hamilton)(Cyprinidae,Cypriniformes)

Keratinized regions were found to occur in the rostral cap, adhesive pad and horny jaw sheaths associated with the lips of Garra lamta, which inhabits fast flowing turbulent hill streams. In these structures, the surface epithelial cells were modified into characteristic keratinized spine‐like or columnar tooth‐like unculi, which would provide firm anchorage for the fish on the substratum and assist the fish in browsing or scraping food materials from it.     

Structure and histochemistry of the normal intestine of the fowl

The fine structures of the development and maturation of intestinal chief cells from the duodenal crypts of the fowl has been described in detail. Three areas within the crypt can be recognised: 1) the crypt base where cell division is frequent but cell development is minimal; (2) the mid-crypt region where rapid growth and development of the cells takes place; and (3) the zone of differentiation where final developments and functional maturation occurs. The structure of the fowl's intestinal crypt is very similar to that described for the mammals. The results are discussed in relation to previous histochemical studies.     

Structure and histochemistry of the dermis of a chequered water snake, Natrix piscator

The histology and the protein, carbohydrate, lipid and enzyme histochemistry of the dermis of the chequered water snake, Natrix piscator , have been examined throughout the sloughing cycle.
The structural organization and staining properties of the dermis do not show any changes in different stages of the cycle.
The dermis is divided into the stratum laxum and the stratum compactum. Acid mucopolysaccharide deposits in the stratum laxum, which possibly bind water, may be involved in prevention of desiccation.
The numerous elastin fibres in the hinge regions are related to the greater elasticity of the skin in these sites.     

Glycoconjugate histochemistry and nNOS immunolocalization in the mantle and foot epithelia of Tapes philippinarum (bivalve mollusc)

Glycosaminoglycans and NO synthase probably regulate mucous cell secretion in the skin of Tapes philippinarum. We have demonstrated the presence of "protein" cells, "glycogen" cells, "phenol" cells and five types of mucous cells, with different chemical composition of the mucus in the mantle epithelium of T. philippinarum. The foot epithelium contained "protein" cells and two types of mucous cells. Using biotinylated lectins, in the mantle and foot epithelia we have shown specific sites for the following oligosaccharides: alpha-D-glucose, alpha-D-mannose, alpha-L-fucose, alpha-D-1,3-N-acetyl-galactosamine and alpha-N-acetyl-glucosamine. nNOS immunoreactivity in the intraepithelial and intradermal cells and in the mucocytes suggested a regulatory role of NO in mucus secretion, as demonstrated also in other invertebrates.     

Monoamine-containing structures in the intestines of bivalve molluscs and a polychaete annelid revealed by fluorescence histochemistry

Summary Monoamine-containing elements in the intestines of Bivalvia and Polychaeta species have been found by use of histochemical fluorescence methods according to Falck and Furness. Catecholamine-containing perikarya and fibers are seen within the epithelium and subepithelial layers of the midgut of the bivalves Mytilus edulis, Mya arenaria, Arctica islandica, as well as the polychaete Harmothoe imbricata. In addition, intraepithelial cell bodies and fibers containing serotonin-like substance are present in Mytilus edulis. Results obtained with the Furness method, applied earlier to vertebrates, correlate with those obtained with the Falck method.     

Ciliated and microvillous structures of rat olfactory and nasal respiratory epithelia

Summary The olfactory epithelium of the Sprague-Dawley rat showed structures which indicate that freeze-substitution after ultra-rapid cryo-fixation is a better method for its preservation than conventional fixation techniques. A new feature is that matrices of the distal parts of olfactory cilia range in their staining intensity from very dense to electron-lucent. Outlines of structures are smooth and membrane features can be clearly seen.The textures of mucus from olfactory and respiratory epithelia are distinctly different after freeze-fracturing and deep-etching following cryo-fixation. Olfactory cilia show no microtubule-attached axonemal structures. Cross-sectional diameters are smaller after freeze-substitution than after freeze-fracturing.Intramembranous particle densities are lower in nine regions of three cell types in cryo-fixed olfactory and respiratory epithelia than in those chemically fixed and cryoprotected. The fracture faces of membranes from etched, cryo-fixed cells have holes, a result which probably accounts for differences in particle density between cryo-fixed and chemically-fixed, cryo-protected cells. Particle diameters are usually the same using both methods. Densities of intramembranous particles and particles plus holes are highest in supporting cell processes, followed by endings and cilia of olfactory receptor cells, and are lowest in respiratory cilia. Particle densities at outer and inner surfaces are higher than those in either fracture face. Outer surfaces show a good correlation from region to region with densities summated over both fracture faces.This work was carried out in the following laboratories: Department of Neurobiology and Physiology, Northwestern University, Evanston, Illinois, USA, Institut für Anatomie, Universitätsklinikum, Essen, FRG, and Psychologisch Laboratorium, Rijksuniversiteit, Utrecht, The Netherlands, and was begun within the Anatomy Section of the 1981 Neurobiology Summer Course at the Marine Biological Laboratories, Woods Hole, Massachusetts, USA     

Structure and carbohydrate histochemistry of the esophagus in ten teleostean species

The histology and carbohydrate histochemistry of ten teleostean esophagi were compared. Structurally, the four layers of a typical vertebrate digestive tract were consistently present. The epithelium was always stratified and in all but one species (Ictalurus nebulosus) contained taste buds. Esophageal mucous cells were not the typical goblet cells seen in other vertebrates but appeared to be of six different types, pairs of which were associated with particular families. In esocids, poorly developed mucous acini and serous monogranular cells were present. In all species, the subepithelial connective tissue was not divided into definitive lamina propriae and submucosae due to the absence of muscularis mucosae. Variably present in this connective tissue region were argentophilic fibers and in esocids only, randomly dispersed striated muscle fibers. The arrangement of the muscularis was reverse to that of the general vertebrate plan. In mucous cells, three general types of epithelial mucosubstances were identified and in broad terms were recognized as sulfomucins, sialomucins and neutral mucosubstances. Morphological differences were accompanied by differences in carbohydrate localization, each esophageal epithelium containing at least two different mucosubstances. However, the mucosubstances identified in each mucous cell had a profile of characteristics different in some respects from any other. Thus teleostean esophagi appear to perform an integrated diversity of functions as reflected by their complex morphology and carbohydrate histochemistry.     

Scanning electron microscopic study of the structures associated with lips of an Indian hill stream fish Garra lamta (Cyprinidae, Cypriniformes)

The surface architecture of the structures associated with the lips of a hill stream fish Garra lamta was examined by scanning electron microscopy. In this teleost, the lips are inconspicuous and associated with prominent horny jaw sheaths. Furthermore, the upper and lower lips are associated with a greatly enlarged rostral cap and an adhesive pad, respectively. The rostral cap has a proximal mucogenic region and a distal keratinized region. The adhesive pad is differentiated into central mucogenic and peripheral keratinized regions. At the mucogenic regions of the rostral cap and the adhesive pad, the surface of the epithelial cells is characterised by well developed microridges, which reflect their high secretory activity. The mucus may lubricate the surface and protect the epithelia from abrasions at these regions, which are likely to be subjected to wear and tear during frequent friction and adhesion of the fish to the substrate. Taste buds may help the fish to locate food and trigger a 'pick-up' reflex. The epithelial cells at the surface of the keratinized regions of the rostral cap and the adhesive pad are modified as clusters of spine like unculi, which may assist the fish in its firm anchorage to the substrate. The epithelial cells at the surface of the horny jaw sheaths are modified as polygonal unculi, each appears much like a tooth that has a characteristic sharp edge at the margin. These may be regarded as an adaptation to browsing or scraping food materials from the substrate.     

Structure and carbohydrate histochemistry of the stomach in eight species of teleosts

The histology and carbohydrate histochemistry of eight teleostean stomachs are compared. Three gross anatomical types of stomachs are described and their shapes appear to correlate somewhat with feeding habits. Each type can be divided histologically into a corpus and pylorus. Gastric glands, containing only one cell type, occur in the copora of all species, but are present in the pylori of esocids only. As a single cell can produce both enzymes and hydrochloric acid such cells may be comparable to those of amphibians but not mammals. Lamina propria and submucosa are indistinctly separated in corpora but better defined in pylori by an intervening muscularis mucosa. The arrangement of the muscularis into inner circular and outer longitudinal layers is the opposite of that seen in the esophagus. Gastric mucous cells show species variations in localization of epithelial mucosubstances, which in broad terms are recognized as sulfomucins, sialomucins and neutral mucosubstances. A piscivorous diet does not appear to demand any particular type of carbohydrate. Within the Centrarchidae, gastric pit cells vary in carbohydrate content from only neutral mucosubstance to only weakly acidic sulfomucin; two species contain both types. A positive PAS reaction on the surface of gastric epithelial cells is suggestive of a striated border and thus possibly absorptive function. The absence of stomachs in some teleosts and the evolutionary and dietary significances are discussed.     

Essence of keratin in lips and associated structures of a freshwater fish Puntius sophore in relation to its feeding ecology: Histochemistry and scanning electron microscope investigation

Morphological specializations in the lips and associated structures of Puntius sophore were examined by scanning electron microscopy and histochemically. The upper lip (UL), in P. sophore, is associated with the horny upper jaw sheath (HUJS) on its ventral side and with the rostral cap (RC) on its dorsal side through a thin and extensive fold of skin (FSUR). The lower lip (LL) is greatly enlarged, conspicuous and associated with horny lower jaw sheath (HLJS) on the dorsal side and ventrally continues with ventral head skin (VHS). On the lateral sides there is a thin and extensive fold of skin (FSLS) between the lower lip and VHS. In contrast to the mucogenic epithelia of the UL, LL, the RC and fold of skins, the horny jaw sheaths are keratinized in nature and surface epithelial cells are characteristically modified into unculi. The UL and the LL are equipped with epithelial cells (EC), mucous cells (MC) and taste buds (TB) while in addition to these cells club cells (CC) are also present in the RC. Keratin found in unculi is an extremely strong protein which is tough and insoluble, they form the hard but un-mineralized structures. Keratin in unculi could be regarded as an adaptation for browsing or scraping food materials from the substrate as the fish grubs about the bottom. The elaboration of mucus is considered to lubricate the surface and protect the epithelia from abrasions. Taste buds are associated to locate and select palatable food and to trigger a ‘pick-up’ reflex.     

Translocation of botulinum neurotoxin serotype A and associated proteins across the intestinal epithelia

Botulinum neurotoxins (BoNTs) are some of the most poisonous natural toxins. Botulinum neurotoxins associate with neurotoxin‐associated proteins (NAPs) forming large complexes that are protected from the harsh environment of the gastrointestinal tract. However, it is still unclear how BoNT complexes as large as 900 kDa traverse the epithelial barrier and what role NAPs play in toxin translocation. In this study, we examined the transit of BoNT serotype A (BoNT/A) holotoxin, complex and recombinantly purified NAP complex through cultured and polarized Caco‐2 cells and, for the first time, in the small mouse intestine. Botulinum neurotoxin serotype A and NAPs in the toxin complex were detectable inside intestinal cells beginning at 2 h post intoxication. Appearance of the BoNT/A holotoxin signal was slower, with detection starting at 4–6 h. This indicated that the holotoxin alone was sufficient for entry but the presence of NAPs enhanced the rate of entry. Botulinum neurotoxin serotype A detection peaked at approximately 6 and 8 h for complex and holotoxin, respectively, and thereafter began to disperse with some toxin remaining in the epithelia after 24 h. Purified HA complexes alone were also internalized and followed a similar time course to that of BoNT/A complex internalization. However, recombinant HA complexes did not enhance BoNT/A holotoxin entry in the absence of a physical link with BoNT/A. We propose a model for BoNT/A toxin complex translocation whereby toxin complex entry is facilitated by NAPs in a receptor‐mediated mechanism. Understanding the intestinal uptake of BoNT complexes will aid the development of new measures to prevent or treat oral intoxications.     

Structure and composition of the oral mucous membrane on the lips and cheeks of the monkey,Macaca fascicularis

Summary In seven monkeys (6 Macaca fascicularis, 1 M. mulatta; 2.4±0.6 kg in weight) the labial and buccal mucosae were studied morphologically and quantitatively. Following fixation by perfusion, the upper and lower lips and entire cheeks were dissected free and processed for light-, scanning and transmission electron microscopy. Established programs (HISTOMEP, MUMANA II) and appropriate morphometric techniques were used to estimate, at the light-microscopic level, the epithelial thickness, the width of the combined lamina propria/submucosa, and the volumetric composition of the gland-containing portions of lip and cheek mucosae. The cheek epithelium was more than twofold thicker than the lip epithelium, on the average 0.46±0.04 and 0.21±0.02 mm, respectively, with no differences related to sex or topographical sites. The combined lamina propria/submuscosa was 1.32 ±0.19 and 1.50±0.26 mm in width in cheeks and lips, respectively. The main mucosal constituents at both sites were glandular and connective tissue, and lymph follicles associated with secretory ducts. In lips, the volume of plasma cells around gland acini correlated positively with the amount of lymphoid tissue present around topographically related ducts. It is suggested that the duct/ lymph follicle assembly may serve as a local antigen-recognition system.

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Zusammenfassung Die Lippen- und Wangenmukosa wurde an 7 Affen (6 M. fascicularis, 1 M. mulatta; 2,4±0,6 kg schwer) morphologisch und quantitativ untersucht. Nach einer Perfusionsfixation wurden Ober- und Unterlippen sowie ganze Wangen herauspräpariert und für Untersuchungen im Licht-, Raster und Transmissionselektronenmikroskop vorbereitet. Bestehende Programme (HISTOMEP, MUMANA II) und morphometrische Standardmethoden wurden verwendet, um lichtmikroskopisch die Epitheldicke, die Breite der kombinierten Lamina propria/Submukosa und die volumetrische Zusammensetzung der drüsenhaltigen Abschnitte der Lippen- und Wangenschleimhaut zu ermitteln. Das Wangenepithel war mehr als zweifach dicker als das Lippenepithel (0,46±0,04 und 0,21±0,02mm); die Epitheldicke war unabhängig von Geschlecht und Topographie. Die kombinierte Lamina propria/ Submukosa war im Wangenbereich 1,32±0,19, im Lippenbereich 1,50± 0,26 mm breit. Die Hauptelemente der Lippen- und Wangenschleimhaut sind Drüsen- und Bindegewebe sowie mit Ausführungsgängen assoziierte Lymphfollikel. In der Lippen-, nicht aber in der Wangenschleimhaut, ist das Volumen der die Drüsenacini umlagernden Plasmazellen positiv korreliert mit der Menge der Lymphfollikel an den benachbarten Ausführungsgängen. Es wird vermutet, daß das Ausführungsgang/Lymphfollikel-System zur lokalen Erkennung von Antigenen dienen könnte.

     

Lens proteome map and alpha-crystallin profile of the catfish Rita rita

Crystallins are a diverse group of proteins that constitute nearly 90% of the total soluble proteins of the vertebrate eye lens and these tightly packed crystallins are responsible for transparency of the lens. These proteins have been studied in different model and non-model species for understanding the modifications they undergo with ageing that lead to cataract, a disease of protein aggregation. In the present investigation, we studied the lens crystallin profile of the tropical freshwater catfish Rita rita. Profiles of lens crystallins were analyzed and crystallin proteome maps of Rita rita were generated for the first time. alphaA-crystallins, member of the alpha-crystallin family, which are molecular chaperons and play crucial role in maintaining lens transparency were identified by 1- and 2-D immunoblot analysis with anti-alphaA-crystallin antibody. Two protein bands of 19-20 kDa were identified as alphaA-crystallins on 1-D immunoblots and these bands separated into 10 discrete spots on 2-D immunoblot. However, anti-alphaB-crystallin and antiphospho-alphaB-crystallin antibodies were not able to detect any immunoreactive bands on 1- and 2-D immunoblots, indicating alphaB-crystallin was either absent or present in extremely low concentration in Rita rita lens. Thus, Rita rita alpha-crystallins are more like that of the catfish Clarias batrachus and the mammal kangaroo in its alphaA- and alphaB-crystallin content (contain low amount from 5-9% of alphaB-crystallin) and unlike the dogfish, zebrafish, human, bovine and mouse alpha-crystallins (contain higher amount of alphaB-crystallin from 25% in mouse and bovine to 85% in dogfish). Results of the present study can be the baseline information for stimulating further investigation on Rita rita lens crystallins for comparative lens proteomics. Comparing and contrasting the alpha-crystallins of the dogfish and Rita rita may provide valuable information on the functional attributes of alphaA- and alphaB-isoforms, as they are at the two extremes in terms of alphaA-and alphaB-crystallin content.