“…All sections were alternately stained with H&E and elastica van Gieson stains as described by Lev. 12 The SAN was unavailable for histopathologic study in 2 cases (cases 8 and 9), the left and right bundle branches were unavailable in 1 case (case 14), and the third portion of the right bundle branch in 2 cases (cases 12 and 13). The percent of SAN cells in relation to fibrous, elastic or fatty tissue was determined under light microscopy.…”