Structure and Distribution of an Unrecognized Interstitium in Human Tissues

The 2018 paper that named the interstitium as a structured, continuous, fluid-filled compartment in human tissues. The lead author Petros C. Benias is a gastroenterologist at Mount Sinai Beth Israel; he worked with David L. Carr-Locke (also GI, a long-time pioneer of endoscopic technique) on probe-based confocal laser endomicroscopy (pCLE). The pathology lead is Neil D. Theise, then holding joint appointments at Mount Sinai Beth Israel and NYU Pathology (now primarily at NYU Grossman School of Medicine) — a hepatobiliary pathologist who also writes on complexity theory and consciousness, and whose collaboration across the anatomy / pathology / endoscopy boundary made the paper's argument possible. Rebecca Wells at Penn and the remaining co-authors provided the histological and structural-biology work.

Published in Scientific Reports in March 2018, the paper is a primary anatomical report with a deliberately bold framing. The finding is that when bile-duct tissue is examined with pCLE in vivo — before the standard slide-preparation process drains the tissue fluid and collapses the spaces — there is a previously unappreciated fluid-filled compartment of collagen-supported sinuses, draining to lymph nodes, present in the submucosae of the entire gastrointestinal tract and urinary bladder, the dermis, the peri-bronchial and peri-arterial soft tissues, and fascia. The Mount Sinai press release named it a new organ. The authors in later interviews — Theise particularly — walked the claim back to a system, not an organ; but the discovery itself is substantively about anatomical visibility: the spaces had been there all along, and the standard preparation method had hidden them.

Scientific Reports is an open-access Nature-family journal with a high-volume editorial filter that is lighter than Nature proper but standard peer review. The piece sits as a primary empirical report, and its claim has two layers. The anatomical claim — these spaces exist, they are continuous, they drain to lymph — is largely uncontested. The framing claim — that this is a new organ or system of clinical significance — is contested, and is what generated the European Journal of Anatomy commentary of 2019 and the authors' reply later that year.

The stake is mixed. The anatomical finding is straightforward science; the new organ framing was promoted heavily by the authors' press office at Mount Sinai and Carr-Locke's clinical network, and the implication for cancer-metastasis modelling — the paper suggests interstitial-space dynamics matter for tumour spread — feeds into ongoing oncology research with substantial funding stakes. Theise's longer-running intellectual interest in the body as a continuous fluid-and-tissue system, which long predates this paper, is the conceptual frame that made the new organ language natural for the authors even if it overstated what the imaging showed. Read it as a primary report whose discovery is solid and whose framing the authors themselves later softened.