Fig. 9. Electron microscopy of the intercalated disc in control and CKO mice. Electron microscopy of the intercalated disc in a control mouse heart (A) shows a gap junction (arrow) in close proximity to adherens junctions (white arrowheads) and desmosomes (black arrowheads), while a representative intercalated disc in a CKO heart (B) shows no gap junctions but intact architecture of the remaining structures. Immuno-electron microscopy for Cx43 in a control heart (C) confirms the presence of Cx43 in the cardiac gap junction and demonstrates the absence of Cx43 label at the intercalated disc of a CKO mouse (D). Immuno-electron microscopy for cadherin in controls (E) and CKO hearts (F) demonstrates intact adherens junctions in both samples. Bars, 50 nm (A,B); 140 nm (C); 70 nm (D); 95 nm (E); 70 nm (F).