Cell growth and anisotropic elongation in engineered silk/collagen/Matrigel hydrogels. (A) Representative IF of mounted myoblast-seeded gels differentiated at time points of 3, 7, and 21 days after seeding shown at 10× with phalloidin (actin) and DAPI staining. Hydrogel-seeded constructs in this series used standard 3D plated culture techniques with no substrate for gel compaction. (B–D) Representative IF of unmounted myoblast-seeded gels differentiated at time points of 3, 7, and 21 days after seeding shown at 10× with phalloidin (actin) and DAPI staining, with printed cantilever insets providing gel mounting (E) shown representatively (F–H). Hydrogel-seeded constructs in the latter series compacted around 3D printed cantilevers. Scale bars: 200 μm. IF, immunofluorescence. Color images available online at www.liebertpub.com/tec