Figure 4: The top row shows light microscope images of NCI-H460 3D culture. (a) (Day 1) demonstrates cells (shown by arrows) that surround the scaffold (dark-shaded areas). This can be compared to (b), which shows that at day 14 multilayers of cells cover the scaffold. The bottom row shows images of H&E staining on paraffin sections of 3D culture after 1 week in culture. (c) shows the complete cross section of a scaffold with most of the large clumps located peripherally (magnification 4x). (d) is an example of a big cluster more than 500 μm in diameter, including a nonviable cell centre region (shown by arrow). The clear region that is marked with an asterisk ( ) shows the location of the scaffold that dissolved in xylene (magnification 20x). Scale bars are (a) 100 μm, (b) 200 μm, (c) 1 mm, and (d) 200 μm.