Fig. 3.

Scanning electron microscope (SEM) imaging of HT-29 and Caco-2 derived spheroids. SEM imaging was performed to assess spheroid morphological parameters in more details. Representative SEM images of spheroids shows roundness structure and smooth surfaces of both a Caco-2 and b HT-29 derived spheroids so that it is not possible to distinguish of individual cells. The hollow structures (arrows) in Caco-2 spheroids is its obvious difference compared to HT-29 spheroids with conglomerated appearance. c Representative phase contrast images of hollow core in Caco-2 derived spheroids. Arrows indicate hollow core of Caco-2 spheroids