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Radial Fibers (radial + fiber)

Distribution by Scientific Domains

Life Sciences	75%

Selected Abstracts

Organization of the connective tissue barrier around long-term loaded implant abutments in man

CLINICAL ORAL IMPLANTS RESEARCH, Issue 5 2002
Gianmario Schierano
Abstract: The study aimed to investigate the connective tissue seal and the spatial organization of collagen fibers around long-term loaded implants in man. Block specimens containing smooth titanium implant abutments and the surrounding supracrestal connective tissue were obtained from patients rehabilitated for at least 1 year with implant-retained overdentures or implant-supported fixed prostheses and were histologically investigated. The histological features of the connective tissue around long-term loaded titanium abutments were specific: the tissue was rich in collagen fibers, organized in bundles, presenting a constant spatial arrangement, similar to that reported in animal studies. Circular fibers, the most numerous, were located externally, and longitudinal fibers internally. Radial fibers inserted on the abutment surface, similar to those of the periodontal system, were not observed in any case. No histological differences were found between tissue sampled around implants supporting a fixed restoration and those anchoring an overdenture. [source]

Reelin, radial fibers and cortical evolution: Insights from comparative analysis of the mammalian and avian telencephalon

DEVELOPMENT GROWTH & DIFFERENTIATION, Issue 3 2009
Tadashi Nomura
The mammalian cerebral cortex has a remarkable laminated structure, which is derived from the pallium, the dorsal part of the embryonic telencephalon. Recent studies indicate that the pallium is developed as a homologous structure in all vertebrate species. However, the cellular and molecular mechanism for making architectural diversity of the pallium is not fully understood. Here we introduce recent progress in comparative analysis of pallial development, and our data on the role of Reelin protein in the developing avian pallium. These experimental approaches to pallial development in non-mammalian species will provide a new insight into evolution of the cerebral cortex. [source]

Glial-guided neuronal migration in P19 embryonal carcinoma stem cell aggregates

JOURNAL OF NEUROSCIENCE RESEARCH, Issue 1 2005
Marcelo F. Santiago
Abstract During development of the nervous system, neuronal precursors that originated in proliferative regions migrate along radial glial fibers to reach their final destination. P19 embryonal carcinoma (EC) stem cells exposed to retinoic acid (RA) differentiate into neurons, glia, and fibroblast-like cells. In this work, we induced P19 aggregates for 4 days with RA and plated them onto tissue culture dishes coated with poly-L-lysine. Several cells migrated out of and/or extended processes from the aggregates after 24 hr. Some cell processes were morphologically similar to radial glial fibers and stained for glial fibrillar acidic protein (GFAP) and nestin. Large numbers of migrating cells showed characteristics similar to those of bipolar migrating neurons and expressed the neuronal marker microtubule-associated protein 2. Furthermore, scanning electron microscopy analysis revealed an intimate association between the radial fibers and the migrating cells. Therefore, the migration of neuron-like cells on radial glia fibers in differentiated P19 aggregates resembled some of the migration models used thus far to study gliophilic neuronal migration. In addition, HPTLC analysis in this system showed the expression of 9-O-acetyl GD3, a ganglioside that has been associated with neuronal migration. Antibody perturbation assays showed that immunoblockage of 9-O-acetyl GD3 arrested neuronal migration in a reversible manner. In summary, we have characterized a new cell culture model for investigation of glial-guided neuronal migration and have shown that 9-O-acetyl GD3 ganglioside has an important role in this phenomenon. © 2005 Wiley-Liss, Inc. [source]

Distinct migratory behavior of early- and late-born neurons derived from the cortical ventricular zone

THE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 1 2004
Yumiko Hatanaka
Abstract Time-lapse studies indicate that ventricular zone (VZ)-derived cells show two migratory modes in the cerebral cortex at different stages of mammalian embryogenesis: somal translocation and locomotion. We carried out a systematic analysis to examine whether the migratory behavior of cortical neurons derived from the cortical VZ is stage-dependent. We labeled VZ cells of mouse embryos with green fluorescent protein (gfp) -encoding plasmids by in utero electroporation and evaluated the labeled cells after appropriate survival periods. After electroporation at either embryonic day (E) 12.5 or E15.5, GFP+ VZ cells were initially spindle-shaped and radially oriented. After leaving the VZ, they transformed into round or horizontally oriented fusiform neurons with many short processes. They then seemed to gradually change into radially oriented bipolar cells as they moved upward. Whereas the earliest emigrants from the VZ labeled at E12.5 (early-born neurons) reached the top of the cortical plate (CP) after these changes, VZ cells labeled at E15.5 (late-born neurons) further migrated along the length of radial fibers to reach the top of the CP. A dominant negative form of the gene for cyclin-dependent kinase 5 (Cdk5DN) was then introduced into VZ cells. Transfection of E12.5 VZ with cdk5dn did not disrupt the migration of the early-born neurons. However, this caused a failure in migration of the late-born neurons, although they transformed into bipolar shapes in the intermediate zone. Thus, there appear to be at least two distinct migratory phases of cortical neurons: one common to the early- and late-born neurons, and the other specific to late-born neurons and Cdk5-dependent. J. Comp. Neurol. 479:1,14, 2004. © 2004 Wiley-Liss, Inc. [source]