Figure 5. (A) Transverse vibratome section of an experimental embryo 48 hr after electroporation of Btg2. Note the abundance of cells positive for β-gal activity in the electroporated limb (*). (B) is a detailed view of the limb electroporated with Btg2. As previously reported, β-gal activity is intense in the AER of both control and experimental limbs, in the mesonephros (M) and in the notochord (N).