Invited:
LIVE IMAGING OF INNER EAR EXPLANTS REVEALS CELLULAR REORGANIZATION UNDERLYING PRECISE PATTERNING IN THE ORGAN OF CORTI

The organ of Corti is one of the most organized tissues in the human body. It consists of four rows of hair cells interspersed by non-sensory supporting cells. The organized pattern of hair cells and supporting cells emerges from a disordered epithelium over a span of a few days. Although a lot is known about the genetic and biochemical processes underlying the development of the organ of Corti, the transition from disordered to ordered pattern is not well understood. We use a combination of quantitative morphological analysis, time lapse confocal imaging of cochlear explants, and laser ablation experiments to elucidate the processes that underlie the transition into an organized pattern. We have developed a set of image analysis tools that allow us to quantify both cell and tissue morphology and obtain quantitative data on cell size, cell shape, and tissue connectivity (e.g. defining the number and identity of neighbors). We use the image analysis to quantify order parameters of the system, to determine cellular flows in the movies, and to analyze mechanical properties of the cells. Based on the analysis, we develop a mathematical model that describes the transition from disordered to ordered pattern in terms of the mechanical forces that act on the cells.