A micromechanical model for the Young’s modulus of adipose tissue

The microstructure of porcine adipose tissue is examined, and a micromechanical model is proposed for the dependence of overall effective modulus upon the moduli of the constituent microstructural units. Scanning electron microscopy and confocal microscopy reveal that the woven collagen network surrounding each adipocyte resembles a closed cell foam of relative density ρ¯m=0.1, while the collagen interlobular septa behave as an open cell foam of relative density ρ¯s=3×10-4. The measured viscosity of the lipid within the adipocytes is η = 36.8 mPa s at 37 °C; this is sufficiently small for the lipid to be idealised as an incompressible inviscid fluid. It is argued that the modulus of adipose tissue is dictated by the collagen network that surrounds the adipocytes. The volume fraction of the interlobular septa is sufficiently low that it provides a negligible contribution to the macroscopic modulus.