Automatic morphometry of nerve histological sections

Abstract

A method for the automatic segmentation, recognition and measurement of neuronal myelinated fibers in nerve histological sections is presented. In this method, the fiber parameters i.e. perimeter, area, position of the fiber and myelin sheath thickness are automatically computed. Obliquity of the sections may be taken into account. First, the image is thresholded to provide a coarse classification between myelin and non-myelin pixels. Next, the resulting binary image is further simplified using connected morphological operators. By applying semantic rules to the zonal graph axon candidates are identified. Those are either isolated or still connected. Then, separation of connected fibers is performed by evaluating myelin sheath thickness around each candidate area with an Euclidean distance transformation. Finally, properties of each detected fiber are computed and false positives are removed. The accuracy of the method is assessed by evaluating missed detection, false positive ratio and comparing the results to the manual procedure with sampling. In the evaluated nerve surface, a 0.9% of false positives was found, along with 6.36% of missed detections. The resulting histograms show strong correlation with those obtained by manual measure. The noise introduced by this method is significantly lower than the intrinsic sampling variability. This automatic method constitutes an original tool for morphometrical analysis.

Differences Exist in the Left and Right Sciatic Nerves of Naïve Rats and Cats

“…Our distributions share similar small diameter peaks to some previous reports using single animals, whereas larger diameter fibers show a broader distribution than previously reported (Romero et al, 2000(Romero et al, , 2001. Our distributions are also broader than those reported for tibial branches (Korthals et al, 1991).…”

“…Although some data, including fascicle areas (Bennett, 1976;Romero et al, 2001;Leventhal et al, 2006), fiber counts (Romero et al, 2001;Leventhal et al, 2006), fiber densities (Branner et al, 2004;Leventhal et al, 2006), mean g-ratio (Friede and Beuche, 1985), and fiber diameter distributions (Romero et al, 2000(Romero et al, , 2001Branner et al, 2004), have been reported, these studies used either small numbers of animals or used data from the contralateral nerve. Additionally, where more than one group has reported data for a specific parameter, the data are often not in agreement.…”

MR properties of excised neural tissue following experimentally induced demyelination

“…Images were captured using a Cool Snap-Pro camera (Media Cybernetics Inc., Silver Springs, MD, USA) and axons larger than 0.5 mm in diameter were analyzed. The analysis involved a threestep approach modeled on the segmentation, recognition and measurement method of Romero et al 19 as previously developed in our laboratory.…”

Neural morphological effects of long-term implantation of the self-sizing spiral cuff nerve electrode

“…However, on some occasions, up to 80% of the entire nerve section was available for the study, in some images, artefacts such as faint fixation, weak osmium impregnation or unhomogeneous staining could be observed. Thresholds were adjusted to overcome these problems (ROMERO et al, 2000). Fibre diameter histograms were constructed for each experimental condition (see Fig.…”