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Fixed Tissue (fixed + tissue)
Selected AbstractsThe orientation and dynamics of cell division within the plane of the developing vertebrate retinaEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 3 2004Marc S. Tibber Abstract The orientation of a dividing cell within the plane of the tissue plays an essential role in regulating cell fate in a range of developing structures. To assess its potential role in the developing vertebrate retina we used standard confocal microscopy of fixed tissue and time-lapse confocal imaging of living tissue to examine the orientation of cell division and mitotic spindle rotation within the plane of the retinal neuroepithelium. Based on the study of three rat strains and chick, we report in contrast to recent findings that during the main phase of cell production (E18,P4 in the rat and E6,E11 in the chick) dividing cells are randomly orientated with respect to key anatomical landmarks as well as the orientation of their dividing neighbours. Results from live imaging of neonatal rat retinae support these findings and suggest that unlike the developing cortex, in which metaphase plates often rotate extensively before coming to rest in anaphase, retinal mitotic spindle rotations prior to cell division are minimal. Furthermore, the orientation of metaphase entry largely defines that which is finally adopted during anaphase. Hence, the dynamics of metaphase progression through to anaphase in the retina appear to differ markedly from the brain, and cell divisions within the plane of the tissue are randomly orientated. These results contribute to a growing body of evidence that suggests that the current paradigm with respect to asymmetric division derived from the study of invertebrates cannot be generalized to the developing vertebrate nervous system. [source] Rapid assessment of internodal myelin integrity in central nervous system tissueJOURNAL OF NEUROSCIENCE RESEARCH, Issue 4 2010Daniel A. Kirschner Abstract Monitoring pathology/regeneration in experimental models of de-/remyelination requires an accurate measure not only of functional changes but also of the amount of myelin. We tested whether X-ray diffraction (XRD), which measures periodicity in unfixed myelin, can assess the structural integrity of myelin in fixed tissue. From laboratories involved in spinal cord injury research and in studying the aging primate brain, we solicited "blind" samples and used an electronic detector to record rapidly the diffraction patterns (30 min each pattern) from them. We assessed myelin integrity by measuring its periodicity and relative amount. Fixation of tissue itself introduced ±10% variation in periodicity and ±40% variation in relative amount of myelin. For samples having the most native-like periods, the relative amounts of myelin detected allowed distinctions to be made between normal and demyelinating segments, between motor and sensory tracts within the spinal cord, and between aged and young primate CNS. Different periodicities also allowed distinctions to be made between samples from spinal cord and nerve roots and between well-fixed and poorly fixed samples. Our findings suggest that, in addition to evaluating the effectiveness of different fixatives, XRD could also be used as a robust and rapid technique for quantitating the relative amount of myelin among spinal cords and other CNS tissue samples from experimental models of de- and remyelination. © 2009 Wiley-Liss, Inc. [source] Diffusion tensor imaging in fixed brain tissue at 7.0 TNMR IN BIOMEDICINE, Issue 2 2003David N. Guilfoyle Abstract The purpose of this work is to assess the feasibility of performing quantitative in vitro brain tissue diffusion tensor imaging (DTI) measurements and to examine their comparability to in vivo measurements. DTI of fixed tissue at high field strength is potentially a very valuable investigative tool as very high spatial resolution can be achieved. DTI was applied to human and mouse brain fixed tissue samples as well as in vivo measurements of the mouse brain. T1 and T2 relaxography of the fixed tissue samples was also performed to provide further characterization of the tissue. All experiments were performed at 7,T. The fractional anisotropy (FA) of the human fixed brain tissue samples is found to be higher in the corpus callosum than in the occipital white matter region, consistent with in vivo measurements reported in the literature. Our FA measurements of the corpus callosum of a mouse brain are also found to be the same both in vitro and in vivo. This preliminary work supports the use of DTI in both fixed human and fixed animal brain tissue as a valid investigative tool. With the increased availability of brain banks in different brain disorders, DTI in fixed tissue may prove to be a very useful method for the study of white matter abnormalities. Copyright © 2003 John Wiley & Sons, Ltd. [source] A re-evaluation of gelsolin at ectoplasmic specializations in sertoli cells: The influence of serum in blocking buffers on staining patternsTHE ANATOMICAL RECORD : ADVANCES IN INTEGRATIVE ANATOMY AND EVOLUTIONARY BIOLOGY, Issue 3 2007Julian A. Guttman Abstract In this study, we test the hypothesis that gelsolin immunolocalized in actin filament-rich ectoplasmic specializations may be exogenous gelsolin present in normal serum used in blocking buffers, and that binds to the intercellular adhesion plaques during tissue processing. Fixed frozen sections of rat and rabbit testis were pre-treated with standard blocking buffers containing 5% normal goat serum (NGS) and then incubated with anti-gelsolin antibodies in the presence of 1% NGS. Other sections were treated in a similar fashion, but in buffers not containing NGS. Sections were then labeled with secondary antibody conjugated to a fluorochrome. Localized staining at ectoplasmic specializations occurred only in sections treated with NGS. The only positive staining in sections not treated with NGS was associated with seminiferous tubule walls and blood vessels in rabbit tissue. The antibodies reacted with a single band at the appropriate molecular weight for gelsolin on immunoblots of NGS, but did not react on immunoblots of testis or seminiferous epithelium. We conclude that gelsolin localized at ectoplasmic specializations using current commercially available antibodies is a result of non-specific binding to the fixed tissues of gelsolin present in blocking buffers. Anat Rec 2007. © 2007 Wiley-Liss, Inc. [source] Laryngeal epithelial thickness: a comparison between optical coherence tomography and histologyCLINICAL OTOLARYNGOLOGY, Issue 5 2009M.L. Kaiser Objectives:, Optical coherence tomography, an imaging modality using near-infrared light, produces cross-sectional tissue images with a lateral pixel resolution of 10 ,m. However, normative data is first needed on epithelial thickness for lesion characterisation, and, to date, little exists. The purpose of our study is to measure normal laryngeal epithelial thickness by in vivo optical coherence tomography, and compare these values to those obtained from fixed ex-vivo laryngectomy specimens. Design and Setting:, Prospective at a single medical center in California, United States. Participants: A total of 116 patients undergoing operative endoscopy. Main outcome measures:, Optical coherence tomography images of clinically normal laryngeal subsites were selected. Calibrated measurements of epithelial thickness at various laryngeal subsites were recorded. Measurements of epithelial thickness from corresponding areas were obtained using optical micrometry on histologically normal regions of 15 total laryngectomy specimens. Descriptive statistics were performed. Results:, Mean epithelial optical coherence tomography thicknesses were: true vocal cords (81 ,m), false vocal cords (78 ,m), subglottis (61 ,m), aryepiglottic folds (111 ,m), laryngeal epiglottis (116 ,m) and lingual epiglottis (170 ,m). Epithelial thicknesses in fixed tissues were: true vocal cords (103 ,m), false vocal cords (79 ,m), aryepiglottic folds (205 ,m) subglottis (61 ,m), laryngeal epiglottis (38 ,m) and lingual epiglottis (130 ,m). Conclusions:, Optical coherence tomography does not have the artifacts associated with conventional histologic techniques. The inevitable development of office-based optical coherence tomography devices will increase the precision of laryngeal measurements and contribute to the clinical application of this technology in diagnosing laryngeal disease. [source] | |||||||||||||