Heart Cells (IMAGE) DOE/Lawrence Berkeley National Laboratory Caption Heart tissue from a normal (wild-type) mouse, with cells stained pink and nuclei in blue, is shown on the left. Hearts from mice missing an important heart enhancer (knockout) exhibit disorganized cell growth, including large spaces between cells (arrow), as shown on the right. Credit UC Davis Comparative Pathology Laboratory Usage Restrictions Commercial use prohibited. License Licensed content 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.