FIG. 2.

The 2.2-kb promoter sequence of the BETA2 gene can direct tissue-specific expression of LacZ in pancreatic islets and neurons of transgenic mice. (A) In the adult transgenic mouse pancreas, β-Gal activity is restricted to well-formed islets of Langerhans (thick arrows) and in small clusters of islet cells (thin arrows). No β-Gal activity is found in exocrine acini (AC), vessels (V), and ducts (D). (B) Whole-mount X-Gal staining of an E11.5 transgenic embryo carrying the BETA2 promoter–lacZ transgene. High levels of β-Gal activity are seen in the dorsal root ganglia (DRG), trigeminal ganglia (TG), neural retina (NR), forebrain (FB), midbrain (MB), and hindbrain (HB). Scale bars equal 200 μm (A) and 40 μm (B).