Fig. 3.

Brightfield micrographs of 3D printed and manually seeded paraffin embedded histological cross sections of a 2 layered air-blood barrier model stained with Masson-Goldner trichrome coloration after 3 days in culture. Cytoplasm is stained red, collagen fibers of the ECM Matrigel^™ green and cell nuclei dark brown. Note the lack of cell organization in the manually seeded compared to the bioprinted model. Scale bars 100 μm. Reproduced in accordance with the Creative Commons Public License (http://creativecommons.org/licenses/by-nc-nd/4.0/) from [34]. Copyright 2015, Springer Nature. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article).