In our podcast Ron and I introduce our conversations as being on the interstitium of innovation, design, technology and behaviour and some other variations on these words.
Interstitium is a rather strange word and most spelling tools don’t really know what to do with it, so I made this page with some perspectives on what it is in the medical space, where the phrase was coined, and also in the conceptual and even the purpose of it in the work space.
Here’s a link to our episode where we talk about the Interstitium for for the first time: https://itsjustamodel.com/2024/01/000_primer/
Blurring the lines, connecting commons, challenging ideas, a bridge between the mechanical and biological.
The interstitium made me (Peet) see a real lexical gap in how to perceive things like design, innovation, technology and behavior as invisibly and fundamentally connected concepts. It made me see what I actually found interesting on ALL these topics together, rather than separately. It was not the minutia of any of these fields, but how they connect.
I found that there are patterns and models that are similar, very self evident, but don’t have a real name and without a steward, role, or function, they might be unexamined, undervalued.
That ‘invisible’ made visible, perspective made it click – a holistic view on how themes and topics intersect, behave similarly and are truly indivisible, because they are in fact connected fundamentally.
The concept of interstitium
To us the interstitium is interesting because it reframes how we think about architecture of the body as a concept, and any analogy of the body, ie organizations, software, complex systems, and more. It’s the area and perspective of our interest.
I like to read these points with the most open interpretation of words like ‘body’ and ‘fluid’ … So, put your literal glasses in their case and as they put it in Dutch, read this as you squint and look for more meaning.
- It blurs the line between “solid” and “fluid.” We tend to picture organs as solid structures with fluid separately flowing through vessels. The interstitium suggests the body is more like a sponge-in-motion: Solid-looking tissue that’s actually a continuously irrigated, semi-fluid mesh.
- It’s a connectivity concept. Rather than organs being isolated units connected only by blood vessels and nerves, the interstitium implies a body-wide, physically continuous space. Almost like an internal “commons” that runs beneath and between everything.
- It challenges the idea that anatomy is fully mapped. Here’s a structure that’s been sitting in plain sight in nearly every tissue sample ever taken, yet its true nature (a connected, functional network) was misunderstood for centuries because of how tissue was prepared for study. That’s a humbling reminder that “known” anatomy can still hide surprises depending on how you look.
- It’s a bridge between mechanical and biological function. Conceptually, it merges the idea of the body as plumbing (fluid transport) with the body as structure (scaffolding, shock absorption): two things usually treated separately.
So as a concept, it’s less “new organ” and more “new way of seeing the spaces between things”, which, as an explorer, might resonate: sometimes the most interesting territory isn’t the landmarks, but what connects them.
The interstitium in our body
This is the original term as I got to know it first, from this Scientific American article. It’s a medical term, but as you can read above, it can be a great metaphor to many other fields, other than medical.
The interstitium is a network of fluid-filled spaces found throughout your body’s connective tissue between organs, under the skin, around muscles, and lining the digestive tract, among other places. Think of it as a sort of interconnected mesh of collagen and elastin fibers that supports tissues while allowing fluid to move through them.
Want to know more? Check out this chatty episode of Radiolab about the Interstium, it also pulls in another perspective by Jennifer Bradel that intersects with some of Peet’s perspectives on the matter.
A few key points:
- It’s not a newly discovered organ, despite some sensational headlines back in 2018. Scientists knew this connective tissue existed, what was new was recognizing it as a continuous, fluid-filled network rather than just “dense connective tissue,” largely thanks to better imaging techniques (like probe-based confocal microscopy on living tissue instead of dehydrated slides for biopsies).
- It may help explain lymphatic drainage, acting as a source of lymph fluid before it enters lymph vessels.
- It’s mechanically important, it acts like a shock absorber, letting tissues flex and move without tearing.
Some researchers proposed calling it an “organ” to highlight its significance, but that’s debated, it’s more accurate to think of it as a structural feature woven throughout nearly all your other organs rather than a standalone one.
Brandel’s invisible work perspective
In her essay Invisible Landscapes, Jennifer Bradel took the body metaphor, and runs with it, from anatomy to labor to ecology to internet platforms. core move: use a biological discovery to expose a blind spot in how we think about everything.
- The body as metaphor source. The interstitium isn’t just fluid and fascia to her, it’s proof that things can be right in front of us, doing essential work, and still go unnoticed simply because our tools (and mindset) weren’t built to see them.
- Naming the unnamed. She coins “interstitionaries”: people who work in the connective spaces between roles, sectors, and institutions rather than occupying a defined slot. The auntie who knows everyone’s birthday. The person quietly linking a city’s hospitals, churches, and volunteers during a crisis. Work that’s real, vital, and completely illegible to résumés and org charts.
- The real target: cell-doctrine. She traces our obsession with discrete units (cells, organs, job titles, departments, industries) back to the invention of the microscope itself, arguing that seeing in “boxes” trained us to think in boxes, and that this shaped not just science but how we organize labor and society.
- What got lost. In focusing on the nouns (the parts), we ignored the verbs (the flow between them), the fluid, relational, dynamic stuff that actually keeps systems alive and communicating. Biologically and socially.
- Her takeaway. If a fluid network hiding in plain sight can rewrite anatomy textbooks, maybe naming our social equivalents (the connectors, the weavers, the in-between workers) can rewrite how we value labor and design institutions. New word, new way of seeing, new way of organizing.
- Not just hopeful. She flags the shadow version too: social media platforms have already mapped our human interstitium and monetized it, sometimes spreading misinformation through it the way cancer spreads through the body’s.
Her bottom line: language shapes perception, and perception shapes systems. Coining “interstitium” for the body gave scientists permission to finally see what was there. She wants a social equivalent, so that connective labor stops being invisible and starts being valued.