Figure 1.

Cluster and spheroid formation. (A) Representative image of MTT cells that spontaneously form clusters when cultured in monolayer. (B) Induction of spheroids by centrifugation of 5 × 10³ MTT cells/well for 10 min at 220 g in 96-well plate with low adherence round bottom. (C) After 48 h, spheroids assume a compact and rigid shape with clear edges, and they can be easily manipulated. In time, it is possible to observe an increase of spheroids mass, and the formation of a necrotic core surrounded by a proliferating cell crown. All images are representative.