Cell Moving through a 3-D Matrix (image) University of Pennsylvania Caption Penn and NIH researchers measured the internal pressure of individual fibroblast cells (in orange) moving through a three-dimensional matrix (in blue). They found that, in this environment, the cells' nuclei operate like an engine's piston to push the cell forward. Credit University of Pennsylvania/NIDCR Usage Restrictions In context of reporting Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.