Histomorphometric analysis of bone lacunae in human and pig: Can it be useful for species discrimination?

Abstract

In recent years, several studies have focused on species identification of bone fragments by the assessment of the histomorphological appearance of bone tissue as well as the quantification of histological structures such as Haversian systems. According to literature, the most consistent distinguishing features are Haversian canal and Haversian system areas. Nonetheless, there is a consistent overlap between human and non-human secondary osteon dimensions. One of the structure that has never been analyzed for the purpose of species discrimination is the bone lacuna, a small oblong cavity in which the osteocyte is locked in. The aim of this study is to verify whether there are significant quantitative differences between human and pig lacunae within secondary osteons with similar areas. Study sample comprises the diaphysis of long bones of a medieval human adult and a subadult pig. A total of 68 secondary osteons with similar areas have been selected for each individual. Each osteon was analyzed with a light microscope and the following measurements were taken at 200X magnification using IScapture® software: 1) total number of lacunae within the osteon, 2) minimum and maximum diameter, area and perimeter of nine lacunae divided between inner, intermediate and outer lacunae. T-test was employed to compare the mean values for the two individuals. The mean number of lacunae per osteon does not seem to be significantly different between human (48.9) and pig (46.9). However, human lacunae seem generally bigger when compared with pig lacunae with a mean area respectively of 45.06 (±17.42) μm2 and 39.6 (± 15.52) μm2. Nonetheless, there is a significant overlap between human and pig. Concerning the differences between inner, intermediate and outer lacunae, the ones close to the cement line (outer lacunae) are clearly bigger when compared with lacunae which are close to the Haversian canal (inner lacunae). Statistical analysis showed a significant difference in the maximum diameter, perimeter and area of the lacunae between human and pig. Though results seem promising, this exploratory study need further research on a bigger sample including individuals of different ages and different species in order to verify its potential for species discrimination.