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Because of the resemblance of many epithelial tissues to densely packed soap bubbles, it has been suggested that surface minimization, which drives soap bubble packing, could be governing cell packing as well. We test this by modeling the shape of the cells in a Drosophila retina ommatidium. We use the observed configurations and shapes in wild-type flies, as well as in flies with different numbers of cells per ommatidia, and mutants with cells where E- or N-cadherin is either deleted or misexpressed. We find that surface minimization is insufficient to model the experimentally observed shapes and packing of the cells based on their cadherin expression. We then consider a model in which adhesion leads to a surface increase, balanced by cell cortex contraction. Using the experimentally observed distributions of E- and N-cadherin, we simulate the packing and cell shapes in the wild-type eye. Furthermore, by changing only the corresponding parameters, this model can describe the mutants with different numbers of cells or changes in cadherin expression. [ABSTRACT FROM AUTHOR]

The adherens junction functions to connect epithelial cells and maintain their polarized architecture. The geometry of the adherens junction, and consequently the shape of a cell, appears to reach an energetically favorable state. Cadherins within the adherens junction are necessary for cells to achieve this state. However, the view of an adherens junction as a static structure is at odds with the highly dynamic properties of epithelia during development. Interactions between the actin cytoskeleton and the adherens junction are required for certain cell shape changes. Recent insights into adherens junction remodeling have revealed the importance of polarized localization of myosin and Par3 at the adherens junction. [Copyright &y& Elsevier]