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1

Electronic Resource

The superposition eye of Cloeon dipterum: The organization of the lamina ganglionaris (1977)

Wolburg-Buchholz, K.

Springer

Cell & tissue research 177 (1977), S. 9-28

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ISSN: 1432-0878

Keywords: Superposition eye ; Lamina ganglionaris ; Cloeon dipterum ; Light- and electron microscopy

Source: Springer Online Journal Archives 1860-2000

Topics: Biology , Medicine

Notes: Summary The lamina ganglionaris of the superposition eye of Cloeon dipterum is composed of separate optic cartridges arranged in a hexagonal pattern. Each optic cartridge consists of one central, radially branched monopolar cell (Li) surrounded by a crown of seven retinula cell terminals and two more unilaterally branched monopolar cells (La1/La2) situated close together outside the cartridge. Projections to neighbouring cartridges have not been observed. In most cases, synaptic contacts could be seen between a presynaptic retinula cell and more than two other postsynaptic profiles, which belong to monopolar cells or sometimes to glial cells. Seven retinula cell fibers of one ommatidium pass in a bundle through the basement membrane, run into their respective cartridges without changing orientation and terminate at approximately equal levels in the lamina. Long visual fibers with endings in the medulla are not visible in the superposition eye lamina, but are present in the lateral apposition eye. The relationship between the behaviour of the animal, optic mechanisms of the superposition eye and the structure of the lamina is discussed.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00221115

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2

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The organization of the lamina ganglionaris of the hemipteran insects, Notonecta glauca, Corixa punctata and Gerris lacustris (1979)

Wolburg-Buchholz, K.

Springer

Cell & tissue research 197 (1979), S. 39-59

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ISSN: 1432-0878

Keywords: Lamina ganglionaris ; First, second order neurons ; Neuroanatomy ; Ultrastructure ; Hemipterans (Notonecta glauca, Corixa punctata, Gerris lacustris)

Source: Springer Online Journal Archives 1860-2000

Topics: Biology , Medicine

Notes: Summary Neuronal elements, i.e. first and second order neurons, of the first optic ganglion of three waterbugs, N. glauca, C. punctata and G. lacustris, are analyzed on the basis of light and electron microscopy. Eight retinula cell axons, leaving each ommatidium, disperse to different cartridges as they enter the laminar outer plexiform layer. Such a pattern of divergence is one of the conditions for neuronal superposition; it is observed for all three species of waterbugs. The manner in which the receptors of a single bundle of ommatidia split of within the lamina, whereby information from receptors up to three or five horizontal rows away can converge upon the same cartridge, differs among the species. Six of the eight axons of retinula cells R1-6, the short visual fibers end at different levels within the bilayered lamina, whereas the central pair of retinula cells R7/8, the long visual fibers, run directly through the lamina to a corresponding unit of the medulla. Four types of monopolar cells L1–L4 are classified; their branching patterns seem to be correlated to the splitting and termination of retinula cell axons. The topographical relationship and synaptic organization between retinula cell terminals and monopolar cells in the two laminar layers are identified by examination of serial ultrathin sections of single Golgi-stained neurons. An attempt is made to correlate some anatomical findings, especially the neuronal superposition, to results from physiological investigations on the hemipteran retina.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00233552

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The synaptic organization of visual interneurons in the lobula complex of flies (1980)

Hausen, K. ; Wolburg-Buchholz, K. ; Ribi, W. A.

Springer

Cell & tissue research 208 (1980), S. 371-387

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ISSN: 1432-0878

Keywords: Lobula complex ; Visual interneurons ; Ultrastructure ; Cobalt-impregnations ; Electron microscopy ; Diptera (Calliphora erythrocephala)

Source: Springer Online Journal Archives 1860-2000

Topics: Biology , Medicine

Notes: Summary The synaptic organization of three classes of cobalt-filled and silver-intensified visual interneurons in the lobula complex of the blowfly Calliphora (Col A cells, horizontal cells and vertical cells) was studied electron microscopically. The Col A cells are regularly spaced, columnar, small field neurons of the lobula, which constitute a plexus of arborizations at the posterior surface of the neuropil and the axons of which terminate in the ventrolateral protocerebrum. They show postsynaptic specializations in the distal layer of their lobula-arborizations and additional presynaptic sites in a more proximal layer; their axon terminals are presynaptic to large descending neurons projecting into the thoracic ganglion. The horizontal and vertical cells are giant tangential neurons, the arborizations of which cover the anterior and posterior surface of the lobula plate, respectively, and which terminate in the perioesophageal region of the protocerebrum. Both classes of these giant neurons were found to be postsynaptic in the lobula plate and pre- and postsynaptic at their axon terminals and axon collaterals. The significance of these findings with respect to the functional properties of the neurons investigated is discussed.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00233871

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4

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Proliferation of smooth muscle cells in the inner and outer layers of the tunica media of arteries: An in vitro study (1991)

Betz, E. ; Fallier-Becker, P. ; Wolburg-Buchholz, K. ; [et al.]

New York, NY [u.a.] : Wiley-Blackwell

Journal of Cellular Physiology 147 (1991), S. 385-395

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ISSN: 0021-9541

Keywords: Life and Medical Sciences ; Cell & Developmental Biology

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Biology , Medicine

Notes: During the development of atherosclerotic and fibromuscular proliferates/lesions, smooth muscle cells (SMC in the media, particularly near the lumen, are activated to migrate into the intima, where they continue to proliferate to form an intimal thickening. It is to date unclear whether SMCs situated adjacent to the adventitia possess a lower capacity to proliferate because they are a special subpopulation of medial SMCs or because the adventitia excerts an inhibitory effect. We have, therefore, developed an in vitro system whereby we have attempted to clear up this uncertainty. The following observations were made from the in vitro experiments:Media-explants from rabbit aorta were laid on a polycarbonate filter with pores 5 μm in diameter. The SMCs migrated through the pores and formed a fibromuscular proliferate on the other side of the filter.Endothelial cells were seeded on one side of the filter before media-explants were laid on the other side of the filter. The confluent endothelium inhibited migration of SMCs through the filter pores.Media-explants were placed between two polycarbonate filters (pores 5 μm diameter). In this “sandwich” arrangement SMCs migrated through both filters, i.e., in both directions. The quantity of migrating and proliferating cells through both filters was almost identical. This suggests that there is no difference in the migratory and proliferate capacity of SMCs in the inner and outer layers in the media of arteries.To investigate the influence of the adventitia on medial SMCs, media-explants were placed between a lower (5 μm) and an upper (0.2 μm) filter adventitia-explants were laid above the media-explants. The 0.2 μm filter prevented migration of SMCs from the media-explant into the adventitia and migration of fibroblasts from the adventitia into the media. Interestingly, the adventitial tissue inhibited proliferation of SMCs at the abluminal and migration and proliferation at the luminal side of the media-explant; the number of cells migrating through the 5 μm pores at the luminal side was diminished, suggesting that the adventitial tissue has an antiproliferative influence on SMCs. Moreover, it was found that in media-explants near the filter with adventitia, the medial SMCs were in a better preserved condition than at the de-endothelialised luminal side.As a control, cultures consisting of media-explants were incubated without filters (i.e., explant organ cultures). The proliferates in the concavity (luminal side) exhibited a pattern of proliferating SMCs different from that of the cells at the abluminal convexity. This finding indicates that the different texture of vessel walls near the adventitia and near the lumen may also influence cell migration and proliferation.

Additional Material: 9 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/jcp.1041470302

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