T cells use a violent breaststroke motion to physically rip through dense tissue as they navigate your body.

T cells were long thought to be passive navigators that simply squeezed through tiny gaps in the body's scaffolding. These immune cells bypass the need for chemical-dissolving enzymes by using finger-like protrusions to grip and pull apart the matrix. The resulting mechanical force is strong enough to create brand-new tunnels through dense barriers that would otherwise be impassable. High-resolution imaging shows the cells exerting localized pressure to rupture the very fibers meant to hold the body together. Future medical interventions will target this mechanical behavior to stop tumors from hijacking these same pathways to spread through the body.