Analysis of Gene Expression Using lacZ Reporter Mouse Lines

Reporter mice transgenically expressing the bacterial (E. coli) lacZ gene encoding β-galactosidase (β-gal, EC 3.2.1.23) are a versatile and extensively used tool to study gene expression and cell lineage patterns. Enzymatic activity of the β-gal reporter can be effectively visualized at cellular resolution either histochemically using 5-bromo-4-chloro-3-indolyl-β-d-galactopyranoside (X-gal) or by immunofluorescent detection using a β-gal-specific antibody. Here, we summarize protocols for the localization of β-gal expressing cells in whole embryos or organs as well as in histological tissue sections of lacZ reporter mice and discuss their limitations and common pitfalls.