Figure 10.

Dense ECM and reduced hydraulic conductivity gives increased detachment of clusters. There is a large heterogeneity seen in (a) showing total cell velocity ${\mathbf{u}}_{\text{c}}$ with a dominating (upstream) cell migration at primary tumor periphery as well as a strong (downstream) migration taking place at the local tumor cell clusters that have been able to break loose from the initial tumor. (a*) (zoomed version of A where focus is on the upper cluster) reveals that there is a net cell velocity at the clusters that squeeze tumor cells toward each other making existing migratory pathways thinner as well as guiding them in the outward direction. (b, b*) Dispersive cell velocity ${\mathbf{u}}_{c,\text{dispersion}}$. (c, c*) The fluid–stress component ${\mathbf{u}}_{c,\text{fluid}-\text{stress}}$ contributes mostly in the peritumoral region and is now a driving force for the outwardly directed migration and toward lymphatics. (d, d*) The chemotactic component ${\mathbf{u}}_{c,\text{chemotaxis}}$ contributes greatly both at the margin of the primary tumor to keep the primary tumor dense and at the local clusters by making them thinner and guiding them toward lymphactis.