Pavement cells in the leaf epidermis of many plant species have intricate shapes that fit together much like the pieces of a jigsaw puzzle. They provide an accessible system to understand the development of complex cell shape. Since a protrusion in one cell must fit into the indentation in its neighbor, puzzle cells are also a good system to study how cell shape is coordinated across a plant tissue. Although molecular mechanisms have been proposed for both the patterning and coordination of puzzle cells, evidence is accumulating that mechanical and/or geometric cues may play a more significant role than previously thought.
Sapala, A., Runions, A., & Smith, R. S. (2019, February 1). Mechanics, geometry and genetics of epidermal cell shape regulation: different pieces of the same puzzle. Current Opinion in Plant Biology. Elsevier Ltd. https://doi.org/10.1016/j.pbi.2018.07.017