Nkx2-5 mutation causes anatomic hypoplasia of the cardiac conduction system
J. Clin. Invest. Patrick Y. Jay, et al. 113:1130 doi:10.1172/JCI19846 [Go to this article.]

Figure 2
Hypoplasia of the central conduction system in heterozygous Nkx2-5 KO mice. Histologic sections of adult hearts demonstrate the blue, X-gal–stained cells of the AV node (A and B) and His bundle (C and D) in WT (A and C) and Nkx2-5^+/neo (B and D) hearts bearing one minK-lacZ allele. The histology of the AV node and His bundle were also examined by H&E and immunohistochemical staining of WT (E, F, I, J) and Nkx2-5^+/– (G, H, K, L) hearts. Cx40 (TRITC, red) and Cx43 (FITC, green) label conductive and contractile myocytes, respectively. The AV node (F and H) and His bundle tissues (J and L) are circled. Consecutive sister sections from the same AV nodes were double-labeled for Cx40 (FITC, green) and Cx45 (TRITC, red) (circled in M and N). In the WT node (M), a small population of Cx40⁺/Cx45⁺ cells is present (arrow), but a larger population bearing Cx45 alone predominates. In the Nkx2-5^+/– node (N) the Cx40⁺/Cx45⁺ cells are present, but the population expressing Cx45 alone is absent. Images shown are representative of at least three separate animals. HET, Nkx2-5^+/– or Nkx2-5^+/neo; AVN, AV node; His, His bundle. Scale bars: 100 μm.