Fig. 1.

Human tendon fibroblasts embedded in a 3D fibrin gel. (A) Tendon fibroblasts display a rounded cell morphology shortly after embedding in fibrin. The image is taken approximately 15 min following cell seeding. Bar: 50 μm. (B) Fibroblasts are expanding and form cellular extensions 180 min following seeding. Bar: 50 μm. (C) Fibroblasts display a thin, elongated cell body and long extensions, the random alignment is seen in the early phase (first three days) of construct formation. Bar: 50 μm. (D) Parallel arrangement of tendon fibroblasts, which are located in between a synthesized matrix with high cellularity. The ordered alignment is visible during the late stage of construct contraction and tissue formation. Bar: 50 μm.