Data from: Secondary osteons scale allometrically in mammalian humerus and femur

Intra-cortical bone remodelling is a cell-driven process that replaces existing bone tissue with new bone tissue in the bone cortex, leaving behind histological features called secondary osteons. While the scaling of bone dimensions on a macroscopic scale is well known, less is known about how the spatial dimensions of secondary osteons vary in relation to the adult body size of the species. We measured the cross-sectional area of individual intact secondary osteons and their central Haversian canals in transverse sections from 40 stylopodal bones of 39 mammalian species (body mass 0.3–21 000 kg). Scaling analysis of our data shows that mean osteonal resorption area (negative allometry, exponent 0.23,R2 0.54,p<0.005) and Haversian canal area (negative allometry, exponent 0.31,R2 0.45,p<0.005) are significantly related to body mass, independent of phylogeny. This study is the most comprehensive of its kind to date, and allows us to describe overall trends in the scaling behaviour of secondary osteon dimensions, supporting the inference that the osteonal resorption area may be limited by the need to avoid fracture in smaller mammalian species, but the need to maintain osteocyte viability in larger mammalian species.

皮质内骨重塑是一种由细胞驱动的过程，该过程在骨皮质中以新骨组织替换原有骨组织，并遗留被称为次级骨单位（secondary osteons）的组织学特征。尽管学界已明确骨尺寸在宏观尺度上的缩放规律，但关于次级骨单位的空间尺寸如何随物种成年体型大小变化的相关认知仍较为匮乏。我们对39个哺乳动物物种（体重范围0.3~21000 kg）的40块肢近侧段骨的组织横切片进行观测，测量了单个完整次级骨单位及其中央哈弗斯管（Haversian canal）的横截面积。对本研究数据的缩放分析显示，平均骨单位吸收面积（负异速生长，指数0.23，决定系数R²=0.54，p<0.005）与哈弗斯管面积（负异速生长，指数0.31，决定系数R²=0.45，p<0.005）均与体重呈显著相关，且不受系统发育关系的影响。本研究是目前同类研究中覆盖范围最全面的一项，我们借此得以阐明次级骨单位尺寸缩放规律的整体趋势，该结果支持如下推论：骨单位吸收面积在小型哺乳动物中受限于避免骨骼骨折的需求，而在大型哺乳动物中则受限于维持骨细胞存活的需求。