Fig. 3.

Approaches to enable 3D architecture for a cell culture production of spheroids in, e.g., hanging drops (a), use of hydrogels (b) of synthetic or natural materials, such as alginate (last picture in B), or use of scaffolds produced from natural materials or synthetically from polymers (c), which are either layered (first picture), electrospun (second picture) or polymerized in a sponge-like structure (third picture)