Cover photograph (Copyright © 2001, American Society for Microbiology. All rights reserved.): Expression of -galactosidase in a kidney from a 15.5-day-old mouse embryo, in which the endogenous Sox8 gene was replaced by the lacZ marker gene. -Galactosidase mimics expression of Sox8 and was visualized in transverse sections through its ability to convert 5-bromo-4-chloro-3-indolyl--D-galactopyranoside into an insoluble blue precipitate. There were no major disturbances of kidney development in the absence of Sox8. (See related article in October 2001, issue 20: vol. 21, p. 6951.)