The cover art for the August 22nd issue of Biophysical Journal was composed with the intention of incorporating elements from both the theoretical and experimental sides of modern biology. It depicts the interstitial space present between cells that adhere to one another with varying degrees of adhesiveness. The top right shows an electron micrograph of a tissue from a frog embryo, in which the interstitial space appears as pale, approximately triangular gaps. One such triangular gap is inset by a 3D representation of a gap derived from our theoretical model, acting as a visual link between theory and experiment. The size and interconnectedness of the modelled interstitial space increases as the eye moves towards the lower left, reflecting the different gap shapes and sizes predicted for different conditions of cell adhesion. The interstitial space is filled with fluid (in fact just over a quarter of the water in the human body is contained in the interstitial space!), and this is reflected in the watery, liquid-like appearance of the model. The electron micrograph and 3D model are reminiscent of the moon and stars – this is meant to invoke a feeling of a new frontier being explored, as biologists move more and more towards mathematical and computational modeling as a means to describe the living world around us. The cover art was produced using Blender, an open-source 3D modeling program, which has helped us to visualize and internalize the geometry of the interstitial space as the model became more complex with more interacting elements.
While our study made use of frog early embryos, interstitial spaces are present in all animals, from invertebrates to vertebrates, and in both diseased and healthy tissues. The interstitial space is involved in fluid balance in the body, transport of metabolites and signaling molecules, and determination of the mechanical properties of a tissue, and it is curious that even in tissues where the cells are very tightly packed, this space is maintained.
—Serge E. Parent, Debanjan Barua, and Rudolf Winklbauer.