Cover photograph (Copyright © 2003, American Society for Microbiology. All Rights Reserved.): Nuclear factor I-C (Nfic) transcripts (purple) in a 14-day-postnatal mouse maxillary molar. Nfic transcripts were detected with a digoxigenin-labeled probe, and the section was counterstained with methyl green to identify cells types. Nfic is highly expressed in developing tooth crown and root odontoblasts and in connective tissue. In Nfic knockout mice, the roots fail to form while the crown appears relatively normal. (See related article in February 2003, issue 3: vol. 23, p. 1075.)