All animals are formed from tissues that bend into complex shapes. The build blocks of these structures are epithelial cells, which pack tightly together to form the lining of blood vessels and organs. We had assumed that these cells adopted prism- or pyramid-like shapes to make such complex structures. However, now Luis Escudero of the University of Seville in Spain and his colleagues have modelled curved tissues where the cells have to “pave” surfaces that have very different areas at their top and bottom.
Particularly, the team wanted to explain a strange finding from previous research showing that epithelial cells can have different types of neighbours at their top and bottom surfaces. The modelling showed that the only way to achieve this pattern was for the cells to adopt a particular prism-like shape with five edges at one end, and six at the other, and with one of the side edges divided into a Y shape. These scutoids slot neatly together, and the paper about this discovery has been published in Nature Communications.
The team also identified scutoids in zebrafish tissues, and a preliminary check found them in mammalian cells too, indicating that they are widely used by nature. The discovery has important implications for tissue engineering and the creation of artificial organs, which rely on understanding and mimicking the 3D organisation of cells.