Expression of the mouse Delta1 gene during organogenesis and fetal development

Cell-to-cell communication mediated by the evolutionary conserved Notch sig nalling pathway regulates cell fate decisions and patterning in various tis sues in diverse organisms (Artavanis-Tsakonas et al., 1995, Science 268, 22 5-232). Signalling between neighboring cells is transduced by binding of DS L and Notch proteins which interact as ligand (DSL) and receptor (Notch). M ouse Delta 1 (delta-like 1; Dll1) encodes one of the four known mammalian D SL proteins and is essential for normal somitogenesis and neuronal differen tiation. Here, we describe Delta1 expression during organogenesis and fetal development using the highly sensitive histochemical detection of the lacZ gene product expressed from a targeted Delta1:lacZ knock-in allele (Dll1(l acZ)). We find that Delta1 is expressed in epithelial ducts of several orga ns, skeletal and smooth muscles, the central nervous system, as well as som e sensory epithelia. (C) 1999 Elsevier Science Ireland Ltd. All rights rese rved.