Liliana Luciano

ber eine ?chemorezeptive? Sinneszelle in der Trachea der Ratte

SummaryIn the tracheal epithelium of adult rats “Brush Border Cells” are found arranged in pairs. Their special structures are narrowly placed and very regular microvilli, the axial filaments of which continue between a number of apical vesicles inside of the cell, without ending in a terminal web. The Golgi apparatus is situated supranuclear; the mitochondria are longitudinally oriented. Ribosomes are free or attached to the membranes of the endoplasmic reticulum. Furthermore there are single and aggregated granules of glycogen and lipid droplets.Along their lateral surface the brush border cells contact initial nerve fibres which contain numerous vesicles, mitochondria, microtubuli and endoplasmatic reticulum.In 14 day-old rats there are found initial nerve fibres in the undifferenciated epithelium. They contain numerous mitochondria with longitudinally oriented cristae. The dendritic branches partly envelope cells that are arranged in pairs like the brush border cells, and also show their typical cytoplasmatic structure. The brush border is missing, since these cells do not reach the free surface of the mucosa. Besides small mitochondria, filaments and numerous ribosomes they contain small accumulations of vesicles (synaptic vesicles) beneath the plasma membrane, on places which lie opposite of a thickened dendritic plasmalemma (postsynaptic membrane).The morphological characteristics of the brush border cells allow to assume that they are chemoreceptors. They make contact with dendrites and form afferent synapses respectively epithelio-neural junctions.Ciliated, goblet and replacement cells are innervated, too. They form contacts with telodendrites, that are efferent synapses or neuro-epithelial junctions and contain structures as they are widely spread in the autonomous nerve system.ZusammenfassungIm Epithel der Trachea der erwachsenen Ratte finden sich paarweise angeordnete „Bürstenzellen“. Ihre strukturellen Besonderheiten sind eng stehende, sehr gleichmäßige Mikrovilli, deren axiale Filamente sich zwischen zahlreichen apikalen Vesikeln innerhalb des Zellkörpers fortsetzen, ohne in einem Terminalgespinst zu enden. Der Golgi-Apparat liegt supranukleär; die Mitochondrien sind längs gerichtet. Außerdem liegen im Zellkörper freie oder an den Membranen des endoplasmatischen Retikulums adsorbierte Ribosomen, einzelne und aggregierte Glykogengranula sowie Fett in Tröpfchenform.Die Bürstenzellen treten entlang ihrer seitlichen Oberfläche mit initialen Nervenfasern in Kontakt, die zahlreiche Vesikel, Mitochondrien, Mikrotubuli und endoplasmatisches Retikulum enthalten.Bei 14 Tage alten Ratten finden sich im noch nicht ausdifferenzierten Epithel initiale Fasern mit einer größeren Anzahl dichter Mitochondrien, die meist längs orientierte Cristae zeigen. Die dendritischen Verzweigungen umhüllen teilweise Zellen, die wie die Bürstenzellen paarweise angeordnet sind und deren cytoplasmatische Struktur besitzen. Der Bürstensaum fehlt, da diese Zellen nicht die freie Oberfläche der Schleimhaut erreichen. Neben kleinen Mitochondrien, Filamenten und zahlreichen Ribosomen enthalten sie unter der Plasmamembran kleine Anhäufungen von Vesikeln (synaptische Vesikel), die gegenüber einer Verdickung (postsynaptische Membran) des dendritischen Plasmalemms liegen.Die morphologische Charakteristika der Bürstenzellen lassen vermuten, daß sie Chemorezeptoren sind. Sie treten in Kontakt mit Dendriten und bilden afferente Synapsen bzw. epithelio-neurale Verbindungen.Auch Flimmerzellen, Schleim- und Ersatzzellen sind reichlich innerviert. Sie weisen Kontakte mit Telodendriten auf, die efferente Synapsen oder neuro-epitheliale Verbindungen darstellen und Strukturen zeigen, wie sie im autonomen Nervensystem weit verbreitet sind.

Ultrastructural architecture of proteoglycans in the glomerular basement membrane. A cytochemical approach.

Rat kidneys were perfused with fixative solutions containing either a) a polycationic dye (Alcian blue 8 GX, Astra blue 6 GLL, cuprolinic blue, ruthenium red), b) a monocationic dye (safranine 0), or c) Alcian blue in the presence of a 0.3 M MgCl2 concentration. Whereas solutions of a revealed the glomerular basement membrane proteoglycans as particles or threads 60 nm apart and arranged in a reticular pattern, solutions of b and c demonstrated new morphological aspects of these molecules. They appeared as tiny filamentous structures, about 100 to 160 nm long, ordered in a network-like pattern with a mesh of about 60-nm width. The filaments displayed lateral branches about 20 nm apart and about 25 nm long, projecting within the meshes. We suggest that the filamentous structures are the protein core, and the branches are the glycosaminoglycans of proteoglycan molecules. Because of this arrangement the negatively charged sites of the glomerular basement membrane would lie closer to each other than previously assumed.

THE FINE STRUCTURAL LOCALIZATION OF ACETYLCHOLINESTERASE ACTIVITY IN THE RETINA AND OPTIC NERVE OF RABBITS

In the rabbit retina acetylcholinesterase activity is localized in the perinuclear cisterna, in the cisternae of the rough surfaced endoplasmic reticulum and in the Golgi apparatus of ganglion cells and amacrine cells. The histochemical reaction is positive also in the rough surfaced endoplasmic reticulum of some horizontal cells. The highest activity is seen in the internal plexiform layer; because of artifacts caused by the diffusion of the enzyme, a clear demonstration of relation of the positivity to one or the other regular components of this layer, however, is not possible. Myelinated fibers which exhibit acetylcholinesterase activity and are most probably efferent are found in the internal plexiform layer. In the retinal nerve fiber layer and in the optic nerve only a few fibers show a positive reaction.

Re-evaluation of Epoxy Resin Sections for Light and Electron Microscopic Immunostaining

Epoxy resins provide optimal tissue morphology at both the light and the electron microscopic level and therefore enable correlative studies on semithin and thin sections from the same tissue block. Here we report on an approach to retain these advantages for immunolabeling studies by adapting and combining well-known techniques, i.e., surface etching with sodium ethoxide and heat-mediated antigen retrieval. We propose a simple procedure for immunostaining semithin and thin epoxy resin sections. To check its applicability, well characterized, commercially available antibodies (against E-cadherin, α-catenin, and β-catenin) were used on sections of human small intestine. By light microscopy, the immunostaining efficiency was compared on cryo-, paraffin, and epoxy semithin sections processed in parallel. The most detailed results were obtained on semithin sections, where the labeling precisely delineated the lateral plasma membrane of the enterocytes. At the electron microscopic level the procedure did not damage the structures and allowed an efficient, reproducible immunogold labeling extending homogeneously over exceptionally wide tissue areas. The three antibodies specifically labeled the zonula adherens of the junctional complex between epithelial cells and, in agreement with light microscopic observations, the lateral plasma membrane.

Bürstenzellen im Alveolarepithel der Rattenlunge

SummaryBetween the alveolar epithelial cells there are cells with the following peculiarities:1.A brush-border with short and thick microvilli.2.Bundles of filaments running from the interior of the microvilli deeply into the cytoplasm.3.Glycogen-particles (β-form). These cells equal morphologically to the brush-cells (probably chemoreceptors) in the trachea and in the rectum of the rat.ZusammenfassungIm Alveolarepithel der Rattenlunge befinden sich Zellen mit folgenden Charakteristika:1.Ein Bürstensaum mit plumpen Mikrovilli.2.Filamente, die in Bündeln aus den Mikrovilli tief in das Cytoplasma hineinragen.3.Glykogen (β-Form). Diese Zellen gleichen morphologisch den Bürstenzellen (vermutlich Chemoreceptoren) der Trachea und des Rectums der Ratte.

Über eine glykogenhaltige Bürstenzelle im Rectum der Ratte

SummaryIn the epithelium of the mucous membrane in the rectum of rats there are some cells with the following pecularities:1.Glycogen-particles which form extended accumulations in young animals, but are singly distributed in adults.2.A brush-border, the microvilli of which are larger and thicker than in the adjoining border cells.3.Bundles of filaments and rows of vesicles in the apical part of the cytoplasm. These glycogen containing brush-cells are very similar to the sensory cells we have described in the epithelium of the trachea of the rat; so far however we have been unable to find connections with dendrites.ZusammenfassungZwischen den gewöhnlichen epithelialen Zellen der Wand des Rectum der Ratte befinden sich Zellen mit folgenden Besonderheiten:1.Glykogenpartikel in Anhäufungen bei jüngeren Tieren, als vereinzelte Granula bei erwachsenen.2.Ein Bürstensaum, dessen Mikrovilli länger und dicker sind als die der anliegenden Saumzellen.3.Filamentbündel und Reihen von Vesikeln im apikalen Zellteil. Diese glykogenhaltigen Bürstenzellen gleichen den Sinneszellen, die wir im Epithel der Trachea der Ratte festgestellt haben; eine Verbindung mit Dendriten konnten wir aber bisher nicht nachweisen.

Massive apoptosis of colonocytes induced by butyrate deprivation overloads resident macrophages and promotes the recruitment of circulating monocytes

Abstract. Our previous investigations demonstrated a rapid, massive apoptosis of colonocytes after butyrate deprivation. However, while in vitro apoptotic bodies and cells were sludged at the epithelial surface, in vivo they were phagocytosed by the resident macrophages. In the present study the guinea pig colon was perfused in vivo in the presence or absence of butyrate with the aim of identifying the cells involved in the removal of apoptotic material and the method of clearance. Morphological, immunohistochemical and DNA fragmentation analyses were applied. The results demonstrated massive apoptosis of colonocytes in the absence of butyrate. The resident macrophages were tightly clustered below the surface epithelium. Aided by cytoplasmatic projections they phagocytosed and transported apoptotic material from the epithelial intercellular spaces into their bodies. Apparently, the macrophages could not cope with the great amount of apoptotic material they had to eliminate: the recruitment of circulating monocytes occurred. This was revealed by the application of antibodies directed against MAC 387, CD68 (PG-M1), and S-100, which detected distinct monocyte/macrophage populations in the lamina propria. The recruited cells were phenotypically different from resident macrophages, their occurrence being typical in inflamed tissues. In conclusion, butyrate deprivation in vivo led to untimely death of colonocytes and triggered changes in the lamina propria indicative of an inflammatory response.

The human gallbladder

The human gallbladder (vesica fellea) is a pear-shaped sac inserted between the under surface of the right lobe of the liver and the peritoneal serous membrane. It consists of three parts or regions: the neck, body (representing the main part of the organ), and fundus (a blind end). The neck is in continuity with the cystic duct, which connects the gallbladder with the common bile duct (ductus choledochus). The lack of morphological information concerning the normal human gallbladder, especially at the level of electron microscopy, was mentioned by Wallraff [1] and remains virtually unchanged to the present day. The reason for this lies in the difficulty or even impossibility of 1) obtaining healthy organs and 2) processing them quickly enough in order to achieve a satisfactory morphology. Most of our present knowledge on the structure and function of the gallbladder stems from studies on animals.

ber die Granula intramitochondrialia

SummaryThe dense granules (granula intramitochondrialia) studied in the mitochondria of the guinea pig kidney show in the proximal and the distal parts of the proximal convolution and in the distal convolution specific differences as to their size and frequency. They contain numerous electron dense particles having a diameter of about 30 Å.

Excessive apoptosis of guinea pig colonocytes may lead to an imbalance between phagocytosis and degradation in vivo

The success or failure of the clearance of apoptotic cell remains depends on the ability of phagocytic cells to recognize, phagocytoze, and digest these remains prior to their lysis, which would cause tissue inflammation. We have recently shown that, after mass-induced apoptosis of guinea pig colonocytes in vivo, phagocytosis by resident macrophages, although efficient, does not prevent a pre-inflammatory response of the mucosa. The present study has investigated the cause(s) of this clearance failure. Immunohistochemistry and transmission electron microscopy were applied. Antibodies directed against the epithelial plasma membrane protein E-cadherin, the lysosomal membrane protein LAMP-1, and the lysosomal matrix protease cathepsin-D were used. The results revealed that: (1) anti-E-cadherin labeled the membrane of epithelial apoptotic bodies internalized in macrophages, (2) double and triple labeling demonstrated that the anti-LAMP-1 and anti-cathepsin-D antibodies recognized and were co-localized in lysosomes and/or phagolysosomes in macrophages but left E-cadherin-positive structures unlabeled, (3) the more numerous were the E-cadherin-positive inclusions in macrophages, the smaller was the number of those that stained positive for lysosomal markers. In parallel with electron microscopy, these findings showed that not all apoptotic bodies phagocytozed by macrophages were subsequently digested, suggesting that the phagocytotic ability of these cells was not matched by their digestive capability.