Symmetry in topography and microstructure of vertebrate skin derivatives

Abstract

Examples of symmetry and asymmetry of ectomesodermal skin derivatives are considered. In biosymmetrics, this question is only mentioned in a few studies. At the same time, in vertebrates, which are characterized by bilateral symmetry of the body, abundant and diverse skin derivatives include various symmetrical and asymmetrical structures. The main objects involved in the study are fish scales (60 species were investigated), plumage (100 species), hair (200 species), and specific skin glands (300 species). An attempt at statistical estimation of symmetry and asymmetry of empirical distribution of morphometric parameters of skin derivatives is undertaken; the symmetry coefficient and coefficient of asymmetry relative to the symmetrical feather of flying and nonflying birds are used. The statistical estimate of symmetry in the sample under study is manifested in the extent of asymmetry of the diagram of normal distribution, whose point of inflection corresponds to the mean value of the sample. Based on these examples, it is proposed that skin derivatives of vertebrates are not only bilaterally symmetrical, which is characteristic of the entire organism, but also show other types of symmetry and asymmetry.