Fig. 6

(A) Schematics showing the procedure of bioprinting perfusable hollow tubes with the cell-encapsulating blend bioink and subsequent vascular formation. Reproduced with permission [84]. Copyright 2016, Elsevier. (B) i) Schematic illustration of tuning of layers of a hollow fiber with multichannel coaxial extrusion system during a 3D bioprinting process. ii) Fluorescence confocal microscopy images showing dynamic conversion between single and double-layered hollow tubes during the bioprinting process (scale bar: 1 cm). Reproduced with permission [85]. Copyright 2018, John Wiley and Sons