Vitreous body rheology

The individual HA molecules are present in solutions in random coil conformation and occupy large hydrated volume. This depends on the molecular mass of HA as well as on its concentration When the concentration increases, the motion of the molecular segments becomes more restricted [143]. As an important consequence, such crowded molecular system has significant viscous and elastic properties. The biological role of the HA in vitreous body and in the joint was interpreted according to these rheological properties [144]. 

Balazs EA. Physiology of the vitreous body. Schepens CL (ed) Importance of the vitreous body in retina surgery with special emphasis on reoperations. St. Louis, C.V. Mosby, 1960, S. 29-48 Balazs EA, Gibbs DA. The rheological properties and biological function of hyaluronic acid, in Balazs EA (ed). Chemistry and Molecular Biology of the Intercellular Matrix, Vol 3. London, Academic Press, 1970, S. 1241-1253... 

Table C3.8 Rheological characteristics of the human vitreous body [21]...

This is a landmark paper on the nature of the vitreous body, describing the mechanochemical (or double-network ) model. This model explains satisfactorily the correlations between some properties of the vitreous (composition, rheology, volume, cell population, transparency) and the physicochemical principles governing its stability (frictional interaction, expansion/contraction, the excluded-volume concept, and the molecular-sieve effect). 

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