Side branch formation and orientation in the caulonema of the moss,Funaria hygrometrica: Experiments with inhibitors and with centrifugation

PROTOPLASMA ◽  
1979 ◽  
Vol 101 (1-2) ◽  
pp. 47-59 ◽  
Author(s):  
G. Schmiedel ◽  
E. Schnepf
Development ◽  
1990 ◽  
Vol 109 (4) ◽  
pp. 753-764
Author(s):  
M.M. McCauley ◽  
P.K. Hepler

Caulonemata of the moss Funaria hygrometrica were vitally stained with the fluorescent, lipophilic carbocyanine dye DiOC6(3) and examined via confocal laser scanning microscopy. Although DiOC6(3) stained nearly all of the organelles, cortical endoplasmic reticulum (ER) could be resolved under favorable conditions and appeared as a network of irregular polygons, interspersed with lamellar cisternae in some cell types. The pattern of cortical ER was examined first during side initial formation and then in young branches and buds. The ER network extends into the outgrowth of a developing side initial, keeping pace with elongation of the outgrowth. Prior to the cell division that cuts off the outgrowth from the underlying cell, the network in the outgrowth becomes tighter, i.e. the polygons become smaller. If the side initial develops as a branch, this somewhat tighter ER network is maintained in the tip-growing side branch. If the side initial develops as a bud, dramatic changes in both the configuration and the quantity of the ER network occur. Coincident with the apical swelling that marks the first visible sign of bud formation, the network becomes increasingly tighter until eventually the polygonal configuration is barely discernible. The increased coverage of the bud cortex by the ER network demonstrates that a significant increase in the quantity of membranes also takes place during bud formation in Funaria.


1991 ◽  
Vol 331 (1261) ◽  
pp. 303-306 ◽  

Four distinct phases can be distinguished in the regenerative response of a lesioned CNS axon: sprouting of the proximal axon stump, elongation, target recognition, and formation of appropriate synapses. These processes can be observed in such a way only in lower vertebrates, in particular, in the optic system. In these species and systems, both, the guidance mechanisms leading regenerating fibres to their former target areas, and the mechanisms responsible for specific synapse formation are retained throughout life. As during development, guidance crucially depends on the presence of favourable substrate molecules, and on chemotropic signals (Dodd & Jessel 1989; Tessier-Lavigne et al .1988; Harris 1989). The cell biological mechanisms responsible for target recognition including the arrest of long-distance growth, the initiation of side branch formation and terminal arborization, and the selection of specific post-synaptic partners (cell type; soma, proximal or distal dendrite, spines, axons) remain unknown up to now.


2011 ◽  
Vol 7 (4) ◽  
pp. 283
Author(s):  
Inga Narbute ◽  
Sanda Jegere ◽  
Indulis Kumsars ◽  
Dace Juhnevica ◽  
Agnese Knipse ◽  
...  

Together with calcified lesions, saphenous vein grafts, chronic total occlusions and unprotected left main lesions, bifurcation lesions are complex lesions that remain among the outstanding challenges of treatment with percutaneous coronary intervention. Bifurcation lesions are associated with increased rates of procedural complications, restenosis and adverse events than lesions in the body of the vessel. The introduction of drug-eluting stents for the treatment of bifurcation lesions has dramatically decreased restenosis rates, especially in patients suffering from diabetes. However, abrupt side branch closure, side branch ostial restenosis and stent thrombosis remain areas where further improvement is needed. Although a provisional T-stent strategy is most often used when side branch stenting is required, there are true bifurcation lesions where the selected use of more complex bifurcation approaches (such as the crush technique, T-stenting or the culotte technique) seem appropriate, particularly when the main branch and side branch are larger vessels with more diffuse side branch disease. The major challenge with any technique is to ensure that the side branch is protected and there is a satisfactory final result. Many technical questions rise in trying to ensure this outcome and lower the risk of intra- and post-procedural complications such as side branch closure and restenosis, stent thrombosis, dissection and fracture of a jailed wire: how can difficult side branch access be solved? How can unfavourable side branch anatomy be re-wired after main vessel stent placement? How can fracture of a jailed wire be avoided? Is side-strut dilation beneficial?


2009 ◽  
Vol 4 (1) ◽  
pp. 70
Author(s):  
Chen Shao-Liang ◽  
Imad Sheiban ◽  
◽  

Coronary bifurcation lesions represent an area of ongoing challenges in interventional cardiology, mainly due to the higher rate of residual stenosis and restenosis at the side branch ostium. Multiple two-stent bifurcation strategies, including T-stenting, V-stenting, simultaneuos kissing stenting, culotte stenting and classic crush techniques, have no advantages over one-stent techniques. This led to provisional stenting being considered as a mainstream approach, based on the results of numerous randomised trials. Dedicated bifurcation stents have been designed specifically to treat coronary bifurcations with the aim of addressing some of the shortcomings of the conventional percutaneous approach and facilitating the provisional approach. The development of more drug-eluting platforms and larger studies with control groups demonstrating their clinical applicability, efficacy and safety are required before these stents are widely incorporated into daily practice.


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