Peter Böck

Localization of Nitric Oxide Synthase I and III in the Cochlea

Nitric oxide synthase (NOS) isoforms I and III were localized in the guinea pig cochlea by indirect immunohistochemistry using frozen sections and paraffin sections. NOS I staining was observed in the cytoplasm of outer hair cells, in nerve cell somata and fibers of the spiral ganglion, and in axonal profiles of the spiral lamina next to the base of inner hair cells. In addition, lining cells of the inner sulcus and limbus, and cells of the spiral ligament stained for NOS I but vascular walls remained unstained. NOS III reactivity was seen in the cytoplasm of outer and inner hair cell, in lining cells of the limbus, and on the endolymphatic surface of marginal cells. Staining for NOS III of spiral ganglion perikarya showed varying intensity. Endothelial cells of cochlear glomeruli reacted for NOS III. NOS III in vascular endothelial cells implies regulatory effects of nitric oxide (NO) on vascular wall tonus and cochlear blood supply. NOS I in cochlear neurons indicates these cells as possible sources for NO during neuronal activity. Activated neurons may provide NO that adjusts cochlear perfusion to neuronal activity. Finally, NO that is liberated from hair cells or afferent synaptic terminals may act as an inhibitor on N-methyl-D-aspartate (NMDA) receptors (negative feed-back inhibition).

Die Feinstruktur der Muskel-Sehnenverbindung von Skelett- und Herzmuskel

Die Feinstruktur der Muskel-Sehnenverbindung in Zunge, Papillarmuskel, M. gastrocnemius und Zwerchfell von Meerschweinchen wurde im Elektronenmikroskop untersucht. In bisher publizierten Arbeiten beschaftigten sich die Autoren vorwiegend mit der Muskelzelle und auβerten die Meinung, Kollagenfibrillen seien fur die Verbindung verantwortlich. Nach unseren Ergebnissen halten wir Mikrofibrillen fur die mechanisch wirksame, zugfeste Komponente der Muskel-Sehnenverbindung. Sie sind einerseits mit der Plasmamembran verbunden, anderseits mit Bundeln von Kollagenfibrillen, die der Basalmembran eng anliegen. An der Plasmamembran verlaufen sie annahernd parallel zueinander, steigen durch die Basalmembran auf und ziehen raumlich ungeordnet in eine zwischen den Kollagenfibrillen liegende Kittsubstanz (Glykoproteide). Die Funktionen der Mikrofibrillen und der sie verankernden Kittsubstanz scheinen zu sein: (a) Die Kraftubertragung von den an der Innenseite der Plasmamembran ansetzenden Aktinfilamenten auf die Kollagenfibrillen der Sehne und (b) Die Milderung des Anfangsruckes bei der Kontraktion des des Muskels.

Memantine for prevention of spinal cord injury in a rabbit model

BACKGROUND This study was conducted to investigate the effect of memantine, a noncompetitive N-methyl-d-aspartate receptor antagonist, on the neurologic outcome of spinal cord ischemia after aortic occlusion. MATERIALS AND METHODS New Zealand White rabbits were anesthetized and spinal cord ischemia was induced for 40 minutes by infrarenal aortic occlusion. Animals were randomly allocated to 3 groups. Group 1 (n = 8, control) received no pharmacologic intervention, group 2 (n = 8) received intra-aortic memantine infusion (20 mg/kg) after aortic crossclamping, and group 3 (n = 8) was treated with systemic memantine infusion (20 mg/kg) 45 minutes before aortic occlusion. Neurologic status was scored by the Tarlov system (in which 4 is normal and 0 is paraplegia) at 12, 24, 36, and 48 hours after the operation. Lumbar spinal root stimulation potentials and motor evoked potentials from lower limb muscles were monitored before, during, and after the operation. After the animals were killed, the spinal cords were studied histopathologically. RESULTS All potentials disappeared shortly after aortic crossclamping. They returned earlier in both memantine-treated groups than in the placebo group. Histologic examination of spinal cords revealed a few abnormal motor neurons in memantine-treated rabbits but found extensive injury in the control group. At 12 hours the median Tarlov scores were 0 in the control group (group 1), 2 in the intra-aortic memantine group (group 2, P =.001 versus control), and 3 in the systemic group (group 3, P =.0002 versus control). At 24 hours median Tarlov scores were 0, 2.5 (P =.0002), and 4 (P =. 0002), respectively. Finally, at both 36 and 48 hours median Tarlov scores were 0, 3 (P =.0006), and 4 (P =.0002), respectively. CONCLUSION Memantine significantly reduced neurologic injury related to spinal cord ischemia and reperfusion after aortic occlusion.

Kontraktile Fibroblasten (Myofibroblasten) in der Lamina propria der Hodenkanälchen vom Menschen

SummaryA special type of fibroblast is observed in the connective tissue of seminiferous tubules in human testes. These cells are characterized by a fibrillar system consisting of parallel arranged cytoplasmic filaments. The filaments have a mean diameter of 80 Å. Bundles of filaments run parallel to the surface of the flattened cells. The filaments insert in a dense, granular material which is connected with the cell membrane. This fibrillar system is thought to be contractile; the dense or more loose texture of the filaments within the bundles may correspond to the contracted or relaxed state of the cell. The specialized fibroblasts described are supposed to belong to the group of myofibroblasts (Gabbiani, Ryan and Majno, 1971).ZusammenfassungIn der Lamina propria menschlicher Hodenkanälchen wurden spezialisierte Fibroblasten beobachtet. Die Zellen sind durch Bündel parallel geordneter Plasmafilamente gekennzeichnet, deren Durchmesser rund 80 Å beträgt. Die Filamentbündel verlaufen parallel zur Oberfläche der lamellär ausgebreiteten Zellen und inserieren in elektronendichtem, granulärem Material, das der Innenseite der Zellmembran anliegt. Es wird angenommen, daß dieses Fibrillensystem kontraktil ist; die dichtere oder lockerere Vernetzung der Filamente innerhalb der Bündel würde dem kontrahierten oder erschlafften Zustand der Zellen entsprechen. Die beschriebenen spezialisierten Fibroblasten sollten der Gruppe der Myofibroblasten zugeordnet werden (Gabbiani, Ryan und Majno, 1971).

Light and electron microscopic identification of elastic, elaunin and oxytalan fibers in human tracheal and bronchial mucosa.

SummaryThe elastic fiber system in the human tracheal and bronchial mucosa was studied by light and electron microscopy. Elastic fibers, elaunin fibers, and oxytalan fibers were discerned. These fibers were identified by means of their staining characteristics (elastica stains, methods for disulfide-groups) and on account of their fine structural morphology. Elastic fibers consist of elastin and few “elastic-fiber microfibrils”. The relative amount of elastin (compared to the amount of elastic-fiber microfibrils) is large in elastic fibers but small in elaunin fibers. Oxytalan fibers — by contrast — are pure bundles of microfibrils.In the light microscope a well-defined elastic lamina separates the lamina propria and the submucosa of the normal mucous membrane. The elastic lamina is formed by coarse strands of longitudinally running elastic fibers. A delicate network of elastica-positive fibers is attached to the basement membrane of the epithelial layer (subepithelial elastic layer). A few of these elastica-positive fibers branch out, traverse the region of the thickened basement membrane, and insert into the basal lamina of the epithelium. A loose network of elastica-positive fibers is present both in the lamina propria and in the submucosa. Plates of cartilage, glandular epithelium, and bundles of smooth muscle cells are enveloped by delicate elastica-positive fibers.Electron microscopy shows the lamina elastica to be predominantly composed of elastic fibers, whilst elaunin fibers from the subepithelial elastic layer. Fibers penetrating the thickened basement membrane of the epithelium are identified as oxytalan fibers. All three types of fibers are present throughout the lamina porpria and in the submucosa. Elaunin fibers and oxytalan fibers comprise the elastica-positive nets around glandular epithelium, smooth muscle bundles, and cartilage. The preferred location of oxytalan fibers (within the thickened basement membrane), elaunin fibers (subepithelial elastica-positive layer), and clastic fibers (lamina elastica) facilitates the comparison of light microscopic staining reactions and fine structural morphology of these fibers.

Myofibroblasts in the rat testicular capsule

SummaryA specialized type of fibroblast occurs in the testicular capsule of adult rats. The flattened cells are characterized by bundles of cytoplasmic filaments. Filament bundles run parallel to the cell surface and insert in plaques of granular, electron dense material which is attached to the inner surface of the plasma membrane (attachment zones). Cytoplasmic filaments measure 60–80 Å in diameter. Sporadically plaques of basal lamina-like material are found, especially in the region of attachment zones.These specialized fibroblasts are interpreted as myofibroblasts. It is supposed that contractility of the testicular capsule in rats is caused by myofibroblasts.

The fine structure of human digital arterio-venous anastomoses (Hoyer-Grosser's organs).

SummaryHoyer-Grossers organs were studied in human digital biopsies. The fine structure of both the supplying arteries and collecting veins was found to be inconspicuous.Endothelial cells in the AV canals form a continuous layer. They are characterized by their rich content of specific organelles (Weibel-Palade bodies), especially in the venous segments. The epitheloid zone is composed of a variety of ramified smooth muscle cells (RSM). These appear either dense, when well provided with bundles of myofilaments, or clear, when including only a few myofilaments. The nuclei of dense RSM show condensed chromatin, while those of clear RSM are larger with loose chromatin texture. In addition, all transitional forms occur. Cell organelles are rarely seen within all types of RSM. The cytoplasmic processes reach each other as well as endothelial cells. The preservation of our material did not allow observation of specialized membrane contacts in these zones. All RSM are invested with a regular basal lamina and well provided with surface vesicles. Profiles of free basal lamina material and faint collagen (argyrophil) fibers are seen in the wide intercellular spaces.RSM poor in myofilaments are interpreted to represent “epitheloid cells” of light microscopy. Their number constantly decreases from the arterial segment of the AV canal to the venous segment. Here the cytoplasmic processes of RSM become less pronounced and the wall of the anastomotic segment continuously changes to that of the collecting vein. Dense RSM rich in myofilaments are compared with pacemaker cells found in the ureter. Both internal and external elastic membranes are absent in AV canals.A dense network of unmyelinated nerve fibers is found in the adventitial layer of the AV canal, especially in its arterial segment. The axons branch out from small dermal nerves which also contain two or three myelinated axons. The myelin sheaths terminate where the axons reach the adventitia of the AV canals. Axon varicosities filled with mitochondria are thought to be terminals of myelinated axons and are interpreted as receptory. Axon varicosities with synaptic-type vesicles are assumed to be terminals of sympathetic and parasympathetic fibers. All axon profiles are confined to the adventitial layer of the anastomotic segment.

Die Feinstruktur des Glomus caroticum beim Menschen

SummaryThe fine structure of the human carotid body is described. The diffuse conglomerations of cells consist of glomus cells and sustentacular cells. The glomus cells show all criteria of chromaffine elements. The sustentacular cells correspond structurally to the cells of Schwann. The fenestrated endothelial cells of the blood vessels point to an active exchange of metabolic substances. No direct contact between glomus cells and the blood vessels is observed. The connective tissue which is rich in nervous material close to the glomus cells is defined as the “stratum nervosum”. The nerves partially end in the stratum nervosum, which is segmented by the cells of the connective tissue and on the other hand reach into the cellparenchyma of the carotid body forming free terminal endings, simple areas of contact and typical synapses with the glomus cells. “Mitochondrial sacs” are described for the first time as nerve receptors. Intraaxonal spaces with an organized structure are described, whose function is not understood.ZusammenfassungDie Feinstruktur des Glomus caroticum des Menschen wird beschrieben (Operationsmaterial). Die disseminierten Parenchymzellhaufen bestehen aus Glomuszellen und Stützzellen. Die Glomuszellen zeigen alle Kriterien chromaffiner Elemente, die Stützzellen entsprechen strukturell den Schwannschen Zellen. Die fenestrierten Endothelien der Gefäße weisen auf einen regen Stoffaustausch hin. Direkte Kontakte zwischen Glomuszellen und Gefäßen kommen nicht vor. Das nervenreiche Bindegewebe um die Glomuszellhaufen wird als „Stratum nervosum“ bezeichnet. Die Nerven endigen z.T. in dem von Bindegewebszellen gekammerten Stratum nervosum, z.T. ziehen sie in das Organparenchym und bilden dort freie Endigungen, einfache Kontaktflächen und typische synaptische Verbindungen mit den Glomuszellen. Erstmals werden „Mitochondriensäcke“ als rezeptorische Endigungen der Nerven und intraaxonale Hohlräume mit geordneten Innenstrukturen beschrieben, deren Funktion unklar ist.

Morphology of the pancreatic duct system in mammals

The morphology of pancreatic excretory duct segments was reviewed in mammals. The fine structure of the epithelial lining was described in intercalated ducts, intra‐ and extralobular ducts, and in major pancreatic ducts. Morphological characteristics of the various cell types comprising to the duct epithelium were detailed. Principal cells in the epithelial linings of interlobular and major pancreatic ducts (“Wirsungiocytes”) were discussed with respect to their appearance as either clear or dark variety. In addition, the capacity of both these cell types in elaborating mucoid glycoprotein secretions was considered and intra‐ and extraepithelial mucoid glands of major pancreatic ducts (ductular glands, accessory glands) was described. Finally, the wall composition of the various excretory duct segments was described. The presence of smooth muscle cells, myofibroblasts, and a peculiar periductal vascular plexus in major interlobular ducts and in main pancreatic ducts was emphasized. Microsc. Res. Tech. 37:407–417, 1997.

Development of pancreas.

Pancreatic development is reviewed in man, mammals, and birds. Anatomical differences and differing topography of pancreatic excretory ducts are described in a series of mammalian species. Species differences are discussed with respect to their embryological significance. The developmental potency of the hepatopancreatic ring is stressed. Cytodifferentiation of exocrine and endocrine cells is considered. Microsc. Res. Tech. 37:374–383, 1997.