Cell size is a defining feature of cell type, and cells have dedicated mechanisms to keep their sizes carefully controlled. Although there is a clear link between size and function at the limits of cell size distribution — such as in erythrocytes, whose small size enables them to navigate the tight confines of capillary networks, or in macrophages, whose large size helps them to engulf a range of targets — the correlation between size and function in the middle range (such as in fibroblasts or epithelial cells) is more ambiguous.