al., 2008; Huebner et al., 2016). The behavior of both the luminal and the myoepithelial cells was followed in real time, showing that mammary ducts elongate through a distinct type of collective epithelial migration, with no leading cell extensions or leading actin-rich protrusions (Ewald et al., 2008). On the whole, these experiments showed that 3D culture systems are an excellent platform to unravel the underlying mechanisms of development, providing the opportunity to understand the context in which they remain normal or go awry and have an impact on disease development.
