Molecular Path from Internal Clock (1 of 2) (image) University of Pennsylvania School of Medicine Share Print E-Mail Caption In left panel, projections from central clock cells (red) in the vicinity of the Upd-expressing nerve cells (green). An enlarged image, right, of the square in left panel. Upd-expressing nerve cells indicated with white arrows. Credit Wenyu Luo, PhD, Perelman School of Medicine, University of Pennsylvania; Cell. Usage Restrictions None Share Print E-Mail 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.