Figure 2.

Proximity of macrophages and myofibroblasts in the septum of the heart from a 20-week fetus with congenital heart block (CHB). Longitudinal sections through the septum of a 20-week CHB heart. Tissue was first incubated with (A) anti-CD68 (macrophage) or (B) anti-smooth muscle actin (myofibroblast and blood vessel smooth muscle cells), and then stained with alkaline phosphatase.