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  • 1
    Electronic Resource
    Electronic Resource
    The desmosome: Fine structural studies with freeze-fracture replication and tannic acid staining of sectioned epidermis (1976)
    Springer
    Cell & tissue research 172 (1976), S. 309-323 
    Details
    ISSN: 1432-0878
    Keywords: Skin ; Epithelia ; Attachment ; Desmosomes ; Freeze-fracture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Desmosomes of larval and post-metamorphic newt epidermis have been studied by freeze-fracture replication both with and without prior glutaraldehyde fixation. Characteristic particles of a diameter (70–130 Å) similar to that of typical membrane associated particles are found clustered on the exposed internal faces of adherent desmosomal membranes. They remain attached to the B-face in unfixed material, but occupy the desmosomal A-face after fixation. Membrane associated particles of nondesmosomal surfaces are found predominantly on the A-face in both fixed and unfixed epidermis. Suitably oriented replicas of unfixed desmosomes reveal profiles of apparent fine filaments extending from the region of tonofilament loops through the desmosomal plaque to traverse the cytoplasmic leaflet of the plasmalemma. They can be traced onto the B-face. Their position correlates to fine linear profiles noted in tannic acid/glutaraldehyde-fixed and sectioned desmosomes. The possibility that these represent a mechanism for anchorage of tonofilaments to the plaque and to the membrane is discussed. These and other fine structural features are compared and contrasted to the properties of hemidesmosomes described in the preceding report.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00399514
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  • 2
    Electronic Resource
    Electronic Resource
    The hemidesmosome: New fine structural features revealed by freeze-fracture techniques (1976)
    Springer
    Cell & tissue research 172 (1976), S. 289-307 
    Details
    ISSN: 1432-0878
    Keywords: Skin ; Epithelia ; Attachment ; Hemidesmosomes ; Freeze-fracture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Hemidesmosomes along the dermal-epidermal junction of larval and post-metamorphic newt skin have been examined in freeze-fracture replica images correlated with electron micrographs of sectioned material. Larval hemidesmosomal sites are characterized by large (200–300 Å) intramembranous granules arranged into clusters, each of which is aligned with a cytoplasmic hemidesmosomal plaque. In unfixed epidermis the granules remain attached to the A-face, while after glutaraldehyde fixation they are found on both A- and B-faces. Following metamorphosis the clusters are less distinct and localized. Replicas of unfixed B-faces and nearby cytoplasm display elongate, filamentous profiles which traverse the cytoplasmic leaflet and extend onto the B-face. The possibility that these components constitute a filamentous network serving to link tonofilaments, hemidesmosomal plaque, and basal plasmalemma is considered in view of the evidence to date. Hemidesmosomal fine structure as revealed by these studies is compared to features of desmosomes as detailed in the following report.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00399513
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  • 3
    Electronic Resource
    Electronic Resource
    Intraorbital cerebrospinal fluid outflow and the posterior uveal compartment of the hamster eye (1985)
    Springer
    Cell & tissue research 240 (1985), S. 77-87 
    Details
    ISSN: 1432-0878
    Keywords: Cerebrospinal fluid ; Aqueous humor ; Choroid ; Meninges ; Golden hamster
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary An ultrastructural and tracer study was undertaken to determine normal outflow pathways of cerebrospinal fluid (CSF) at the terminal subarachnoid space (SAS) of the optic nerve. In the morphological studies, the optic nerve dura and arachnoid were found to be continuous with the sclera of the eye beyond the optic nerve SAS. The pia mater is continuous with the inner sciera and the lamina fusca of the eye. Montages and serial sections demonstrated that the distal SAS is divided into numerous tortuous channels to form an “arachnoidal trabecular meshwork”. Spaces of this meshwork continue into “microcanals” which bypass the outer arachnoid barrier layers of the optic nerve meninges to reach the sclera and posterior intraorbital connective tissue. Ferritin infused into the cisterna magna entered the optic nerve SAS within 1 min and reached arachnoidal trabecular meshwork channels and the microcanals within 8 min. It then passed into intraorbital connective tissue spaces at the posterior pole of the eye. Ferritin appeared to be blocked by the lamina fusca and a newly discovered “posterior compact zone” which together prevented its entrance into the choroidal interstitium. These observations suggest that a “ subarachnoidal-scleral-orbital outflow pathway” provides a route for CSF drainage from the optic nerve SAS to intraorbital connective tissue. The previously described “posterior uveal compartment” in the hamster eye (Kelly et al. 1983) appears to be relatively isolated from this subarachnoidal-scleral-orbital CSF outflow.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00217560
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  • 4
    Electronic Resource
    Electronic Resource
    Structural analysis of potential barriers to bulk-flow exchanges between uvea and sclera in eyes of Macaque monkeys (1990)
    Springer
    Cell & tissue research 260 (1990), S. 459-468 
    Details
    ISSN: 1432-0878
    Keywords: Choroid, ocular ; Uvea ; Eyes, lateral ; Macaca fascicularis, Macaca mulatta ; Macaca nemestrina (Primates)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The uveal tract of the eyes of monkeys was examined by electron microscopy using both thin sections and freeze-fracture replicas. The ultrastructural features of the lamina fusca in the monkey resembled those previously described for rabbit. The lamina fusca was composed of numerous interleaved processes of fibroblastic and pigmented cells and contained tight junctions between fibroblastic cell processes that were predominantly discontinuous, as well as numerous fenestrations through the attenuated cell processes. There was no regional compaction of cellular processes traversing the entire uvea at the level of the ora serrata as reported previously in hamster eyes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00297225
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  • 5
    Electronic Resource
    Electronic Resource
    Structural analysis of potential barriers to bulk-flow exchanges between uvea and sclera in eyes of rabbits (1990)
    Springer
    Cell & tissue research 259 (1990), S. 255-263 
    Details
    ISSN: 1432-0878
    Keywords: Choroid, ocular ; Uvea ; Aqueous humor ; Eyes, lateral ; Rabbit (Lagomorpha)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The uveal tract of rabbit eyes was examined using transmission electron microscopy of thin sections and freeze-fracture replicas. Emphasis was placed on the organization of pigmented and fibroblastic cells near the ora serrata and more generally in the lamina fusca, since these regions were previously found to restrict ingress of tracer molecules to the choroid in hamster eyes. There were significant differences between rabbit and hamster in the disposition of the pigmented cells and fibroblastic layers, the extent and patterns of tight junctions adjoining fibroblastic cells, and the presence of vesicles or fenestrations in the attenuated fibroblastic cell processes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00318447
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  • 6
    Electronic Resource
    Electronic Resource
    Uveoscleral permeability to intracamerally infused ferritin in eyes of rabbits and monkeys (1992)
    Springer
    Cell & tissue research 270 (1992), S. 559-567 
    Details
    ISSN: 1432-0878
    Keywords: Choroid, ocular ; Uvea ; Eyes, lateral ; Ferritin ; Rabbit (Lagomorpha) ; Macaca fascicularis (Primates)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The permeability of the uveoscleral outflow pathway from the anterior ocular chamber was examined in rabbit and monkey eyes using anionic ferritin as a tracer. Ferritin, infused intracamerally, had ready access to the choroidal interstitium, and the degree of penetration was generally correlated with the time and pressure relationships during infusion. In both species, there were accumulations of tracer in intercellular spaces at the lamina fusca, but tracer was also present in the sclera. Thus, in contrast to the situation in the eyes of hamsters, the uveoscleral outflow pathway in the eyes of rabbits and monkeys includes the choroidal connective tissue and allows passage of relatively large molecular weight substances.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00645059
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  • 7
    Electronic Resource
    Electronic Resource
    Fibrillar and cytoskeletal substructure of tight junctions: Analysis of single-stranded tight junctions linking fibroblasts of the lamina fusca in hamster eyes (1984)
    Springer
    Cell & tissue research 238 (1984), S. 545-557 
    Details
    ISSN: 1432-0878
    Keywords: Tight junctions ; Zonulae occludentes ; Choroid ; Fibroblasts ; Cytoskeleton ; Golden hamster
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The lamina fusca of the hamster eye contains layers of flattened, slightly overlapping fibroblasts. Thin sections of the overlapping margins reveal punctate, tight-junction-like membrane appositions associated with accumulation of cytoplasmic filaments, 5–7 nm in diameter. Intermediate filaments are present in the surrounding cytoplasm. A diffuse dense substance occurs in adjacent intercellular space. Freeze-fracture replicas show that the membrane appositions are mainly single-stranded tight junctions, each composed of two fibrils (micelles), and each continuous or nearly continuous around the fibroblastic perimeter. Fracturing characteristics of these junctions offer a unique opportunity to gain further insight into tight junctional morphology. When exposed, the fibrils adhere to the P-face, measure 9.2±0.3 nm in diameter, and are accompanied by a narrow band of membrane differing in texture from non-junctional membrane. Characteristically, the junctional fibrils themselves mark the deviation line along which fracture planes pass from one membrane of the junction to the other. This pattern exposes, over long distances, the P-face of one membrane on one side of this line and E-face of the adjacent membrane on the other. Analysis of any single junction over such distances reveals that the juxtaposition of the fibrils may gradually twist or undulate over a range of at least 180° within the two involved membranes. The fracture plane appears preferentially to pass between the two junctional fibrils; association of the cytoskeleton with junctional fibrils may govern this route of fracture. Cytoskeletal attachment appears to be to a single fibril and may alternate from one fibroblast to the next depending on which cytoplasmic leaflet is nearest a given fibril.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00219871
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  • 8
    Electronic Resource
    Electronic Resource
    Cytological and histochemical investigations on the pineal organ of the adult frog (Rana esculenta) (1960)
    Springer
    Cell & tissue research 52 (1960), S. 618-639 
    Details
    ISSN: 1432-0878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary 1. Among the various cellular components of the epiphysis described in adult Rana esculenta, the sensory cells seem to display a spectrum of images in their outer segments after careful fixation. 2. A histochemical analysis has revealed, in addition to an active lipid metabolism and accumulation, the presence of sulfonic acid, glycol, or perhaps acid mucopolysaccharide components in the outer segments of sensory cells and in the pineal lumen. The possible relationships of these materials to sensory or secretory functions of the cells have been considered. 3. Observations by means of silver stains have shown that sensory cells possess the usual neural characteristics of a sensory epithelium, and also a secondary and possibly efferent innervation. This finding has been discussed in relation to the question of secretion. 4. Since the efferent type of innervation is seen on both sensory and parenchymal types of cells, the classification of the latter as of supportive origin has been questioned. 5. Sensory cells have been found in clustered arrangement not only in the epiphyseal lumen, but also in close proximity to the subcommissural organ. These posterior pineal clusters display protuberances extending into the third ventricle. 6. Epiphyseal follicles with a cystein- or cystine-rich protein component in their secretion have been described. The origin and possible functions of such follicles have been discussed especially in relation to the subcommissuralorgan.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00339850
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  • 9
    Electronic Resource
    Electronic Resource
    The pineal organ of the newt; a developmental study (1962)
    Springer
    Cell & tissue research 58 (1962), S. 693-713 
    Details
    ISSN: 1432-0878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The normal development and cytology of the pineal organ in the newt, Taricha torosa has been described in detail. Particular emphasis has been placed on the origin of the initial pineal bud in the embryonic diencephalic roof, and the manner in which new pineal cells are proliferated in a zone surrounding the orifice of the developing pineal vesicle. These new cells apparently migrate into the walls of the enlarging vesicle and a certain number undergo progressive differentiation to become photoreceptor-like pineal sensory cells; the highest degree of this differentiation being obtained by cells whose processes protrude into the anterior, posterior, and lateral margins of the vesicle lumen. The well-formed, wide-lumened vesicle typical of early larval stages has thusfar not demonstrated any detectable cytological alterations under the influence of light, dark, pressure, or chemical stimulating agents we have employed. Within a few weeks, this young larval vesicle becomes flattened to assume the appearance of a more glial vascularized organ. In adult pineal organs it has been possible to observe aldehyde fuchsin-positive accumulations in the processes of supportive cells terminating near capillary walls. Other aspects of adult pineal cytology and innervation have also been considered in this report. A series of implants of embryonic pineal primordia into older larval host eye chambers and tailfins has given information on the development of vesicles in these sites under the influence of varying amounts of diencephalic roof tissue included with the grafts. A tentative hypothesis has been formulated to account for the tendency of a single primordium to differentiate into a larger than normal pineal mass when implanted into the tail mesenchyme with a moderate amount of diencephalic roof tissue. This hypothesis brings into focus the normal growth characteristics of the young organ developing from a broad initial pineal field and their possible modification under the influence of surrounding tissues during normal ontogeny. Incidental to the main purposes of the study, observations have been made on the pigment behavior of larvae carrying supernumerary pineal implants. These observations are discussed in the light of recent proposals by other authors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00410657
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  • 10
    Electronic Resource
    Electronic Resource
    An ultrastructural analysis of the paraphysis cerebri in newts (1964)
    Springer
    Cell & tissue research 64 (1964), S. 778-803 
    Details
    ISSN: 1432-0878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Paraphyses from the brains of adult Triturus pyrrhogaster and adult and larval Taricha torosa have been examined by light and electron microscopy. Adjacent epithelial cells of the CSF-filled paraphyseal saccules are partially separated by extensive intercellular compartments containing variable amounts of granular, electron dense material. Each compartment is open basally against the basement membrane but narrows apically to a tight junction. Finger-like projections of neighboring cells interdigitate across the compartments. Toward the apical surface of the epithelium, the interdigitations are attached to each other by numerous desmosomes. The interdigitations and basal infoldings of the plasma membrane impart a paraphyseal morphology resembling cells known to be involved in fluid transport. Luminal surfaces often bulge and are microvillous near tight junctions. A single cilium is common. Interior cytoplasmic components include scattered mitochondria, smooth and rough endoplasmic reticulum, Golgi complexes, basal lipid accumulations, and variable amounts of glycogen granules. External to the epithelial cells, unmyelinated nerve bundles course through the connective tissue separating the epithelium from the underlying venous sinusoidal network. Presumed mast cells are present in the connective tissue in addition to fibroblasts. Thorotrast particles (colloidal thorium dioxide) introduced into the venous sinusoids rapidly traverse the endothelium and accumulate at the basement membrane of the paraphyseal epithelium. After two hours, the smallest particles of the tracer suspension have penetrated the basement membrane and are found scattered through the length of the intercellular compartments. Thorotrast neither invades cytoplasmic components of the epithelium nor crosses tight junctions to enter the CSF, even when the particles circulate for as long as nine hours before fixation. These findings are discussed in relation to previous light microscopical examinations and theories on possible paraphysis function.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00323310
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