Usefulness of scanning electron microscope for observation of compact bone structure and saw mark

Abstract

　In forensic anthropology, the histological structure of compact bone is useful for distinguishing human from non-human bone and for age estimation. A saw mark on the bone surface is also analyzed to estimate the implement that cut the bone. However, extensive time and technical proficiency are required to prepare a specimen for obtaining a clear image of the compact bone structure in optical microscopy. Moreover, clear detection of a saw mark is inhibited by the limited focal depth of optical microscopy and by the color tone of bones. The purpose of this study is to evaluate imaging mode of scanning electron microscope (SEM) and preparation of bone specimen to readily obtain a clear image of the compact bone structure and saw mark in a shorter time. In this paper, a transverse section of a long bone was polished to a mirror finish, completed within a few minutes by a simple method, to observe the compact bone structure. In consequence, Haversian canal, bone lacuna, and lamellar structure in the compact bone were clearly observed with compositional (COMPO) image in the backscattered electron mode. Meanwhile, the saw mark was also clearly recognized as a convexo-concave on the transverse section of the long bone with topographic (TOPO) image in the backscattered electron mode. Thus, SEM is useful to observe the compact bone structure and saw mark simply, rapidly, and clearly for practical use in forensic anthropology.