Tumour microtissue architecture.

<p>Semi-thin sections (1 μm slices) of A549/Colo699 mono- and co-cultures after ten days of cultivation stained with toluidine. Bar in all pictures: 20 μm. A549 cells form rugged spheroids resembling a more multi-layered tissue and exhibit a rough surface. Colo699 monocultures reveal a spheroidal structure with a loose surface. When fibroblasts are added both cell lines build a more compact microtissue with a regular surface.