Exciting developments in terms of three-dimensional culture systems such as intestinal (Dekkers et al. 2013; Schwank et al. 2013) or cerebral (Lancaster et al. 2013) organoids allow analysis of cell–cell interactions in a more complex mixture of cell types with some underlying tissue architecture (Huch and Koo 2015; Lancaster and; Knoblich 2014; Passier et al. 2016). Such systems have been exploited to uncover cellular phenotypes underlying microcephaly (Lancaster et al. 2013) and cystic fibrosis (Dekkers et al. 2013; Schwank et al. 2013), respectively. Although progress is being made in organ reconstruction of structures such as the integumentary system is being made (Takagi et al. 2016), it is unlikely that very complex tissues will be able to be modelled successfully in vitro at least in the near future.
