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.

皮质内骨重建是一种细胞介导的生物学过程，指在骨皮质内以新骨组织替换原有骨组织，并留下被称为次级骨单位（secondary osteons）的组织学特征。尽管宏观尺度下骨尺寸的缩放规律已被广泛认知，但学界对次级骨单位的空间维度如何随物种成体体型变化仍知之甚少。我们对39种哺乳动物（体重范围0.3~21000千克）的40块肢体近端长骨的横切片进行测量，统计了完整单个次级骨单位及其中央哈弗斯管（Haversian canals）的横截面积。对数据的缩放分析显示，次级骨单位吸收面积（负异速生长，指数0.23，R²=0.54，p<0.005）与哈弗斯管面积（负异速生长，指数0.31，R²=0.45，p<0.005）均与体重呈显著相关，且不受系统发育关系影响。本研究是目前同类研究中覆盖范围最广的一项，得以阐明次级骨单位维度缩放规律的整体趋势，同时支持以下推论：在体型较小的哺乳动物中，次级骨单位吸收面积受限于避免骨骼骨折的需求；而在体型较大的哺乳动物中，则受限于维持骨细胞活性的需求。