Cross Section Morphology of Seed Coat of Beans Observed by Scanning Electron Microscope.

Abstract

Foods and their related materials found in gastric contents or illegal industrial wastes sometimes play important roles in cases of murder, industrial and environmental crimes. Though the observation of starch by the light transmitted microscope has been frequently carried out for the forensic purpose, the shape of starch is sometimes diminished by putrefaction or digestion. Seed coats are considered to remain in their shapes against the operation of decomposition in comparison to starch and their textures may be preserved in such severe conditions. Nevertheless, detail examinations had not been carried out from the forensic point of view. For the forensic discrimination of beans, cross section morphology of seed coats was examined using the scanning electron microscope (SEM). In this examination, the morphology of seed coat textures of nine kinds of beans obtained in eastern Japan were observed. The cross sections of seed coats were prepared using a razor blade and coated with gold for the observation by SEM. Palisade parenchyma and hourglass cells of hypodermis were observed using XL30 scanning electron microscope (FEI, USA). Thicknesses of these cells were measured, and they were characteristic to each species. Inter-species discrimination among these samples was possible by comparing the ratio of thickness of palisade parenchyma and hourglass cell. Intra-species variation was recognized in four different kinds of soybean samples by the comparison of the ratio of cells and the shapes of hourglass cells. As a result, discrimination among the samples, except two soybeans, was possible by the morphological comparison of seed coat of beans. All samples discriminated each other by the combination with macrographical observation of their color. By these results, the morphological comparison of textures of seed coats by SEM was useful for forensic discrimination of beans.