In this image, cellular interstitial space is represented via the negative--the space around the blood vessel and proteins diffusing across the cellular membrane. While recently lauded as the "newfound organ" (Benias et al. 2018), the interstitium--the contiguous fluid-filled space connected by a protein lattice--remains elusive. Characterized by its inbetweenness, the interstitial is located relative to its location to other, more material structures. In its relative immateriality, the interstitial is understood only through its ability to be filled with excess fluid or pathogenic cells. For U.S. veterans exposed to burn pits--large pits used on U.S. military bases to burn war-related waste using jet fuel--interstitial lung diseases are common, though still poorly understood.
Benias, Petros C., Rebecca G. Wells, Bridget Sackey-Aboagye, Heather Klavan, Jason Reidy, Darren Buonocore, Markus Miranda et al. "Structure and distribution of an unrecognized interstitium in human tissues." Scientific reports 8, no. 1 (2018): 1-8.