Retinal ganglion cells in the eastern newtNotophthalmus viridescens: Topography, morphology, and diversity

Morphometry of cellular behavior of coelomocytes from starfish Asterias amurensis

A comprehensive statistical analysis using a wide range of linear and non-linear morphological parameters enabled identification of the main stages in the in vitro dynamics of cell behavior of immune cells of the marine invertebrate Asterias amurensis (Echinodermata, Asteroidea). Three stages may be distinguished in the cell behavior, which are characterized by the differences in complexity of the cell boundary microsculpture as well as by the size and asymmetry of the cell and convex hull of the cell. The first stage (5 min after placing cells onto a substrate) is characterized by more complex cell morphology and an increase in the process number and spreading area. The second stage (15 min) is characterized by simplification of cell morphology, retraction of some processes, and rounding of cells upon continued cell spreading. At the third stage (60 min), new large processes with rounded contours emerge due to partial retraction of the flattened cell surface. Each stage is characterized by statistically significant differences in several linear and nonlinear parameters of the external morphology for all cell types.

Understanding the retinal basis of vision across species

The vertebrate retina first evolved some 500 million years ago in ancestral marine chordates. Since then, the eyes of different species have been tuned to best support their unique visuoecological lifestyles. Visual specializations in eye designs, large-scale inhomogeneities across the retinal surface and local circuit motifs mean that all species' retinas are unique. Computational theories, such as the efficient coding hypothesis, have come a long way towards an explanation of the basic features of retinal organization and function; however, they cannot explain the full extent of retinal diversity within and across species. To build a truly general understanding of vertebrate vision and the retina's computational purpose, it is therefore important to more quantitatively relate different species' retinal functions to their specific natural environments and behavioural requirements. Ultimately, the goal of such efforts should be to build up to a more general theory of vision.

Description and classification of bivalve mollusks hemocytes: a computational approach

The fractal formalism in combination with linear image analysis enables statistically significant description and classification of "irregular" (in terms of Euclidean geometry) shapes, such as, outlines of in vitro flattened cells. We developed an optimal model for classifying bivalve Spisula sachalinensis and Callista brevisiphonata immune cells, based on evaluating their linear and non-linear morphological features: size characteristics (area, perimeter), various parameters of cell bounding circle, convex hull, cell symmetry, roundness, and a number of fractal dimensions and lacunarities evaluating the spatial complexity of cells. Proposed classification model is based on Ward's clustering method, loaded with highest multimodality index factors. This classification scheme groups cells into three morphological types, which can be distinguished both visually and by several linear and quasi-fractal parameters.

Analysis of the shapes of coelomocytes of Aphelasterias japonica in vitro (Echinodermata: Asteroidea)

A description and formal classification of in vitro spreading coelomocytes from the Aphelasterias japonica sea star was performed using 39 parameters of linear and nonlinear morphometry based on the correlation, factor, and cluster analysis. The comparison of a variety of clustering models revealed the optimum classification parameters and algorithms. As a result, four morphological types of spreading cells significantly differing in a number of structural parameters were identified. This approach may be an important alternative or addition to classical methods of classification of polymorphic, irregularly shaped cells, in particular, cell elements of the invertebrate immune system. It provides the optimum methodology for structural analysis and classification of cells as a part of their further investigation in terms of structure, function, ontogeny, and diversity.

Comparison of eye morphology and retinal topography in two species of New World vultures (Aves: Cathartidae)

Vultures are highly reliant on their sensory systems for the rapid detection and localization of carrion before other scavengers can exploit the resource. In this study, we compared eye morphology and retinal topography in two species of New World vultures (Cathartidae), turkey vultures (Cathartes aura), with a highly developed olfactory sense, and black vultures (Coragyps atratus), with a less developed sense of olfaction. We found that eye size relative to body mass was the same in both species, but that black vultures have larger corneas relative to eye size than turkey vultures. However, the overall retinal topography, the total number of cells in the retinal ganglion cell layer, peak and average cell densities, cell soma area frequency distributions, and the theoretical peak anatomical spatial resolving power were the same in both species. This suggests that the visual systems of these two species are similar and that vision plays an equally important role in the biology of both species, despite the apparently greater reliance on olfaction for finding carrion in turkey vultures.